def ipynbformat(lines):
"""Converts raw file lines to the JSON content lines used in ipynb"""
line = repr(lines[0])[1:-1].replace('"', r'\"')
alllines = line + '",\n'
for i in range(1, len(lines) - 1):
line = repr(lines[i])[1:-1].replace('"', r'\"')
alllines += ' "' + line + '",\n'
line = repr(lines[-1])[1:-1].replace('"', r'\"')
alllines += ' "' + line
return alllines.replace(r"\'", r"'")
def ipynbformat(lines):
"""Converts raw file lines to the JSON content lines used in ipynb"""
line = repr(lines[0])[1:-1].replace('"', r'\"')
alllines = line + '",\n'
for i in range(1, len(lines)-1):
line = repr(lines[i])[1:-1].replace('"', r'\"')
alllines += ' "' + line + '",\n'
line = repr(lines[-1])[1:-1].replace('"', r'\"')
alllines += ' "' + line
return alllines.replace(r"\'", r"'")
def r_a_ratio(ucell):
"""
Calculates the r/a ratio by identifying the shortest interatomic spacing, r,
for a unit cell.
Parameters
----------
ucell : atomman.System
The unit cell system to evaluate.
Returns
-------
float
The shortest interatomic spacing, r, divided by the unit cell's a
lattice parameter.
"""
r_a = ucell.box.a
for i in range(ucell.natoms):
for j in range(i):
dmag = np.linalg.norm(ucell.dvect(i,j))
if dmag < r_a:
r_a = dmag
return r_a / ucell.box.a
def r_a_ratio(ucell):
"""
Calculates the r/a ratio by identifying the shortest interatomic spacing, r,
for a unit cell.
Parameters
----------
ucell : atomman.System
The unit cell system to evaluate.
Returns
-------
float
The shortest interatomic spacing, r, divided by the unit cell's a
lattice parameter.
"""
r_a = ucell.box.a
for i in range(ucell.natoms):
for j in range(i):
dmag = np.linalg.norm(ucell.dvect(i, j))
if dmag < r_a:
r_a = dmag
return r_a / ucell.box.a
def parsefunctions(lines):
"""
Parses out the lines of a Python script corresponding to primary functions.
"""
name = None
for i in range(len(lines)):
if lines[i].strip() != '':
if lines[i][0] != ' ' and name is not None:
yield name, lines[start:i]
name = None
if lines[i][:4] == 'def ':
start = i
name = lines[i][4:].split('(')[0].strip()
def parsefunctions(lines):
"""
Parses out the lines of a Python script corresponding to primary functions.
"""
name = None
for i in range(len(lines)):
if lines[i].strip() != '':
if lines[i][0] != ' ' and name is not None:
yield name, lines[start:i]
name = None
if lines[i][:4] == 'def ':
start = i
name = lines[i][4:].split('(')[0].strip()
def peierlsnabarrostress(pnsolution,
delta_tau,
tausteps=1,
cdiffstress=False,
fullstress=True,
min_method='Powell',
min_options={}):
"""
Applies stress to a semi-discrete Peierls-Nabarro solution.
"""
total_energies = []
tau_xys = []
tau_yys = []
tau_yzs = []
# Loop over stress states
for i in range(0, tausteps + 1):
tau = i * delta_tau
pnsolution.solve(tau=tau,
cdiffstress=cdiffstress,
fullstress=fullstress,
min_method=min_method,
min_options=min_options)
sys.stdout.flush()
# Save values
total_energies.append(pnsolution.total_energy())
tau_xys.append(tau[1, 0])
tau_yys.append(tau[1, 1])
tau_yzs.append(tau[1, 2])
# Save solution to file
model = pnsolution.model()
with open(os.path.join(str(i) + '.json'), 'w') as f:
model.json(fp=f)
# Initialize results dict
results_dict = {}
results_dict['total_energy'] = total_energies
results_dict['tau_xy'] = tau_xys
results_dict['tau_yy'] = tau_yys
results_dict['tau_yz'] = tau_yzs
return results_dict
def elastic_constants_static(lammps_command,
system,
potential,
mpi_command=None,
strainrange=1e-6,
etol=0.0,
ftol=0.0,
maxiter=10000,
maxeval=100000,
dmax=uc.set_in_units(0.01, 'angstrom')):
"""
Repeatedly runs the ELASTIC example distributed with LAMMPS until box
dimensions converge within a tolerance.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
strainrange : float, optional
The small strain value to apply when calculating the elastic
constants (default is 1e-6).
etol : float, optional
The energy tolerance for the structure minimization. This value is
unitless. (Default is 0.0).
ftol : float, optional
The force tolerance for the structure minimization. This value is in
units of force. (Default is 0.0).
maxiter : int, optional
The maximum number of minimization iterations to use (default is 10000).
maxeval : int, optional
The maximum number of minimization evaluations to use (default is
100000).
dmax : float, optional
The maximum distance in length units that any atom is allowed to relax
in any direction during a single minimization iteration (default is
0.01 Angstroms).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'a_lat'** (*float*) - The relaxed a lattice constant.
- **'b_lat'** (*float*) - The relaxed b lattice constant.
- **'c_lat'** (*float*) - The relaxed c lattice constant.
- **'alpha_lat'** (*float*) - The alpha lattice angle.
- **'beta_lat'** (*float*) - The beta lattice angle.
- **'gamma_lat'** (*float*) - The gamma lattice angle.
- **'E_coh'** (*float*) - The cohesive energy of the relaxed system.
- **'stress'** (*numpy.array*) - The measured stress state of the
relaxed system.
- **'C_elastic'** (*atomman.ElasticConstants*) - The relaxed system's
elastic constants.
- **'system_relaxed'** (*atomman.System*) - The relaxed system.
"""
# Convert hexagonal cells to orthorhombic to avoid LAMMPS tilt issues
if am.tools.ishexagonal(system.box):
system = system.rotate([[2, -1, -1, 0], [0, 1, -1, 0], [0, 0, 0, 1]])
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Get lammps version date
lammps_date = lmp.checkversion(lammps_command)['date']
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data',
f='init.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(system.symbols)
lammps_variables['strainrange'] = strainrange
lammps_variables['etol'] = etol
lammps_variables['ftol'] = uc.get_in_units(ftol, lammps_units['force'])
lammps_variables['maxiter'] = maxiter
lammps_variables['maxeval'] = maxeval
lammps_variables['dmax'] = uc.get_in_units(dmax, lammps_units['length'])
# Fill in template files
template_file = 'cij.template'
lammps_script = 'cij.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
template_file2 = 'potential.template'
lammps_script2 = 'potential.in'
with open(template_file2) as f:
template = f.read()
with open(lammps_script2, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run LAMMPS
output = lmp.run(lammps_command, lammps_script, mpi_command)
# Pull out initial state
thermo = output.simulations[0]['thermo']
pxx0 = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy0 = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz0 = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz0 = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz0 = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy0 = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Negative strains
cij_n = np.empty((6, 6))
for i in range(6):
j = 1 + i * 2
# Pull out strained state
thermo = output.simulations[j]['thermo']
pxx = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Calculate cij_n using stress changes
cij_n[i] = np.array([
pxx - pxx0, pyy - pyy0, pzz - pzz0, pyz - pyz0, pxz - pxz0,
pxy - pxy0
]) / strainrange
# Positive strains
cij_p = np.empty((6, 6))
for i in range(6):
j = 2 + i * 2
# Pull out strained state
thermo = output.simulations[j]['thermo']
pxx = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Calculate cij_p using stress changes
cij_p[i] = -np.array([
pxx - pxx0, pyy - pyy0, pzz - pzz0, pyz - pyz0, pxz - pxz0,
pxy - pxy0
]) / strainrange
# Average symmetric values
cij = (cij_n + cij_p) / 2
for i in range(6):
for j in range(i):
cij[i, j] = cij[j, i] = (cij[i, j] + cij[j, i]) / 2
# Define results_dict
results_dict = {}
results_dict['raw_cij_negative'] = cij_n
results_dict['raw_cij_positive'] = cij_p
results_dict['C'] = am.ElasticConstants(Cij=cij)
return results_dict
def relax_static(lammps_command, system, potential, mpi_command=None,
p_xx=0.0, p_yy=0.0, p_zz=0.0, p_xy=0.0, p_xz=0.0, p_yz=0.0,
dispmult=0.0, etol=0.0, ftol=0.0, maxiter=10000,
maxeval=100000, dmax=uc.set_in_units(0.01, 'angstrom'),
maxcycles=100, ctol=1e-10):
"""
Repeatedly runs the ELASTIC example distributed with LAMMPS until box
dimensions converge within a tolerance.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
p_xx : float, optional
The value to relax the x tensile pressure component to (default is
0.0).
p_yy : float, optional
The value to relax the y tensile pressure component to (default is
0.0).
p_zz : float, optional
The value to relax the z tensile pressure component to (default is
0.0).
p_xy : float, optional
The value to relax the xy shear pressure component to (default is
0.0).
p_xz : float, optional
The value to relax the xz shear pressure component to (default is
0.0).
p_yz : float, optional
The value to relax the yz shear pressure component to (default is
0.0).
dispmult : float, optional
Multiplier for applying a random displacement to all atomic positions
prior to relaxing. Default value is 0.0.
etol : float, optional
The energy tolerance for the structure minimization. This value is
unitless. (Default is 0.0).
ftol : float, optional
The force tolerance for the structure minimization. This value is in
units of force. (Default is 0.0).
maxiter : int, optional
The maximum number of minimization iterations to use (default is 10000).
maxeval : int, optional
The maximum number of minimization evaluations to use (default is
100000).
dmax : float, optional
The maximum distance in length units that any atom is allowed to relax
in any direction during a single minimization iteration (default is
0.01 Angstroms).
pressure_unit : str, optional
The unit of pressure to calculate the elastic constants in (default is
'GPa').
maxcycles : int, optional
The maximum number of times the minimization algorithm is called.
Default value is 100.
ctol : float, optional
The relative tolerance used to determine if the lattice constants have
converged (default is 1e-10).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'relaxed_system'** (*float*) - The relaxed system.
- **'E_coh'** (*float*) - The cohesive energy of the relaxed system.
- **'measured_pxx'** (*float*) - The measured x tensile pressure of the
relaxed system.
- **'measured_pyy'** (*float*) - The measured y tensile pressure of the
relaxed system.
- **'measured_pzz'** (*float*) - The measured z tensile pressure of the
relaxed system.
- **'measured_pxy'** (*float*) - The measured xy shear pressure of the
relaxed system.
- **'measured_pxz'** (*float*) - The measured xz shear pressure of the
relaxed system.
- **'measured_pyz'** (*float*) - The measured yz shear pressure of the
relaxed system.
"""
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Get lammps version date
lammps_date = lmp.checkversion(lammps_command)['date']
# Save initial configuration as a dump file
system.dump('atom_dump', f='initial.dump')
# Apply small random distortions to atoms
system.atoms.pos += dispmult * np.random.rand(*system.atoms.pos.shape) - dispmult / 2
# Initialize parameters
old_vects = system.box.vects
converged = False
# Run minimizations up to maxcycles times
for cycle in range(maxcycles):
old_system = deepcopy(system)
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data', f='init.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(system.symbols)
lammps_variables['p_xx'] = uc.get_in_units(p_xx, lammps_units['pressure'])
lammps_variables['p_yy'] = uc.get_in_units(p_yy, lammps_units['pressure'])
lammps_variables['p_zz'] = uc.get_in_units(p_zz, lammps_units['pressure'])
lammps_variables['p_xy'] = uc.get_in_units(p_xy, lammps_units['pressure'])
lammps_variables['p_xz'] = uc.get_in_units(p_xz, lammps_units['pressure'])
lammps_variables['p_yz'] = uc.get_in_units(p_yz, lammps_units['pressure'])
lammps_variables['etol'] = etol
lammps_variables['ftol'] = uc.get_in_units(ftol, lammps_units['force'])
lammps_variables['maxiter'] = maxiter
lammps_variables['maxeval'] = maxeval
lammps_variables['dmax'] = uc.get_in_units(dmax, lammps_units['length'])
# Set dump_modify_format based on lammps_date
if lammps_date < datetime.date(2016, 8, 3):
lammps_variables['dump_modify_format'] = '"%d %d %.13e %.13e %.13e %.13e"'
else:
lammps_variables['dump_modify_format'] = 'float %.13e'
# Write lammps input script
template_file = 'minbox.template'
lammps_script = 'minbox.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run LAMMPS and extract thermo data
logfile = 'log-' + str(cycle) + '.lammps'
output = lmp.run(lammps_command, lammps_script, mpi_command, logfile=logfile)
thermo = output.simulations[0]['thermo']
# Clean up dump files
os.remove('0.dump')
last_dump_file = str(thermo.Step.values[-1]) + '.dump'
renamed_dump_file = 'relax_static-' + str(cycle) + '.dump'
shutil.move(last_dump_file, renamed_dump_file)
# Load relaxed system
system = am.load('atom_dump', renamed_dump_file, symbols=system.symbols)
# Test if box dimensions have converged
if np.allclose(old_vects, system.box.vects, rtol=ctol, atol=0):
converged = True
break
else:
old_vects = system.box.vects
# Check for convergence
if converged is False:
raise RuntimeError('Failed to converge after ' + str(maxcycles) + ' cycles')
# Zero out near-zero tilt factors
lx = system.box.lx
ly = system.box.ly
lz = system.box.lz
xy = system.box.xy
xz = system.box.xz
yz = system.box.yz
if np.isclose(xy/ly, 0.0, rtol=0.0, atol=1e-10):
xy = 0.0
if np.isclose(xz/lz, 0.0, rtol=0.0, atol=1e-10):
xz = 0.0
if np.isclose(yz/lz, 0.0, rtol=0.0, atol=1e-10):
yz = 0.0
system.box.set(lx=lx, ly=ly, lz=lz, xy=xy, xz=xz, yz=yz)
system.wrap()
# Build results_dict
results_dict = {}
results_dict['dumpfile_initial'] = 'initial.dump'
results_dict['symbols_initial'] = system.symbols
results_dict['dumpfile_final'] = renamed_dump_file
results_dict['symbols_final'] = system.symbols
results_dict['E_coh'] = uc.set_in_units(thermo.PotEng.values[-1] / system.natoms,
lammps_units['energy'])
results_dict['lx'] = uc.set_in_units(lx, lammps_units['length'])
results_dict['ly'] = uc.set_in_units(ly, lammps_units['length'])
results_dict['lz'] = uc.set_in_units(lz, lammps_units['length'])
results_dict['xy'] = uc.set_in_units(xy, lammps_units['length'])
results_dict['xz'] = uc.set_in_units(xz, lammps_units['length'])
results_dict['yz'] = uc.set_in_units(yz, lammps_units['length'])
results_dict['measured_pxx'] = uc.set_in_units(thermo.Pxx.values[-1],
lammps_units['pressure'])
results_dict['measured_pyy'] = uc.set_in_units(thermo.Pyy.values[-1],
lammps_units['pressure'])
results_dict['measured_pzz'] = uc.set_in_units(thermo.Pzz.values[-1],
lammps_units['pressure'])
results_dict['measured_pxy'] = uc.set_in_units(thermo.Pxy.values[-1],
lammps_units['pressure'])
results_dict['measured_pxz'] = uc.set_in_units(thermo.Pxz.values[-1],
lammps_units['pressure'])
results_dict['measured_pyz'] = uc.set_in_units(thermo.Pyz.values[-1],
lammps_units['pressure'])
return results_dict
def relax_static(lammps_command,
system,
potential,
mpi_command=None,
p_xx=0.0,
p_yy=0.0,
p_zz=0.0,
p_xy=0.0,
p_xz=0.0,
p_yz=0.0,
dispmult=0.0,
etol=0.0,
ftol=0.0,
maxiter=10000,
maxeval=100000,
dmax=uc.set_in_units(0.01, 'angstrom'),
maxcycles=100,
ctol=1e-10):
"""
Repeatedly runs the ELASTIC example distributed with LAMMPS until box
dimensions converge within a tolerance.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
p_xx : float, optional
The value to relax the x tensile pressure component to (default is
0.0).
p_yy : float, optional
The value to relax the y tensile pressure component to (default is
0.0).
p_zz : float, optional
The value to relax the z tensile pressure component to (default is
0.0).
p_xy : float, optional
The value to relax the xy shear pressure component to (default is
0.0).
p_xz : float, optional
The value to relax the xz shear pressure component to (default is
0.0).
p_yz : float, optional
The value to relax the yz shear pressure component to (default is
0.0).
dispmult : float, optional
Multiplier for applying a random displacement to all atomic positions
prior to relaxing. Default value is 0.0.
etol : float, optional
The energy tolerance for the structure minimization. This value is
unitless. (Default is 0.0).
ftol : float, optional
The force tolerance for the structure minimization. This value is in
units of force. (Default is 0.0).
maxiter : int, optional
The maximum number of minimization iterations to use (default is 10000).
maxeval : int, optional
The maximum number of minimization evaluations to use (default is
100000).
dmax : float, optional
The maximum distance in length units that any atom is allowed to relax
in any direction during a single minimization iteration (default is
0.01 Angstroms).
pressure_unit : str, optional
The unit of pressure to calculate the elastic constants in (default is
'GPa').
maxcycles : int, optional
The maximum number of times the minimization algorithm is called.
Default value is 100.
ctol : float, optional
The relative tolerance used to determine if the lattice constants have
converged (default is 1e-10).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'relaxed_system'** (*float*) - The relaxed system.
- **'E_coh'** (*float*) - The cohesive energy of the relaxed system.
- **'measured_pxx'** (*float*) - The measured x tensile pressure of the
relaxed system.
- **'measured_pyy'** (*float*) - The measured y tensile pressure of the
relaxed system.
- **'measured_pzz'** (*float*) - The measured z tensile pressure of the
relaxed system.
- **'measured_pxy'** (*float*) - The measured xy shear pressure of the
relaxed system.
- **'measured_pxz'** (*float*) - The measured xz shear pressure of the
relaxed system.
- **'measured_pyz'** (*float*) - The measured yz shear pressure of the
relaxed system.
"""
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Get lammps version date
lammps_date = lmp.checkversion(lammps_command)['date']
# Save initial configuration as a dump file
system.dump('atom_dump', f='initial.dump')
# Apply small random distortions to atoms
system.atoms.pos += dispmult * np.random.rand(
*system.atoms.pos.shape) - dispmult / 2
# Initialize parameters
old_vects = system.box.vects
converged = False
# Run minimizations up to maxcycles times
for cycle in range(maxcycles):
old_system = deepcopy(system)
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data',
f='init.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(
system.symbols)
lammps_variables['p_xx'] = uc.get_in_units(p_xx,
lammps_units['pressure'])
lammps_variables['p_yy'] = uc.get_in_units(p_yy,
lammps_units['pressure'])
lammps_variables['p_zz'] = uc.get_in_units(p_zz,
lammps_units['pressure'])
lammps_variables['p_xy'] = uc.get_in_units(p_xy,
lammps_units['pressure'])
lammps_variables['p_xz'] = uc.get_in_units(p_xz,
lammps_units['pressure'])
lammps_variables['p_yz'] = uc.get_in_units(p_yz,
lammps_units['pressure'])
lammps_variables['etol'] = etol
lammps_variables['ftol'] = uc.get_in_units(ftol, lammps_units['force'])
lammps_variables['maxiter'] = maxiter
lammps_variables['maxeval'] = maxeval
lammps_variables['dmax'] = uc.get_in_units(dmax,
lammps_units['length'])
# Set dump_modify_format based on lammps_date
if lammps_date < datetime.date(2016, 8, 3):
lammps_variables[
'dump_modify_format'] = '"%d %d %.13e %.13e %.13e %.13e"'
else:
lammps_variables['dump_modify_format'] = 'float %.13e'
# Write lammps input script
template_file = 'minbox.template'
lammps_script = 'minbox.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(
iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run LAMMPS and extract thermo data
logfile = 'log-' + str(cycle) + '.lammps'
output = lmp.run(lammps_command,
lammps_script,
mpi_command,
logfile=logfile)
thermo = output.simulations[0]['thermo']
# Clean up dump files
os.remove('0.dump')
last_dump_file = str(thermo.Step.values[-1]) + '.dump'
renamed_dump_file = 'relax_static-' + str(cycle) + '.dump'
shutil.move(last_dump_file, renamed_dump_file)
# Load relaxed system
system = am.load('atom_dump',
renamed_dump_file,
symbols=system.symbols)
# Test if box dimensions have converged
if np.allclose(old_vects, system.box.vects, rtol=ctol, atol=0):
converged = True
break
else:
old_vects = system.box.vects
# Check for convergence
if converged is False:
raise RuntimeError('Failed to converge after ' + str(maxcycles) +
' cycles')
# Zero out near-zero tilt factors
lx = system.box.lx
ly = system.box.ly
lz = system.box.lz
xy = system.box.xy
xz = system.box.xz
yz = system.box.yz
if np.isclose(xy / ly, 0.0, rtol=0.0, atol=1e-10):
xy = 0.0
if np.isclose(xz / lz, 0.0, rtol=0.0, atol=1e-10):
xz = 0.0
if np.isclose(yz / lz, 0.0, rtol=0.0, atol=1e-10):
yz = 0.0
system.box.set(lx=lx, ly=ly, lz=lz, xy=xy, xz=xz, yz=yz)
system.wrap()
# Build results_dict
results_dict = {}
results_dict['dumpfile_initial'] = 'initial.dump'
results_dict['symbols_initial'] = system.symbols
results_dict['dumpfile_final'] = renamed_dump_file
results_dict['symbols_final'] = system.symbols
results_dict['E_coh'] = uc.set_in_units(
thermo.PotEng.values[-1] / system.natoms, lammps_units['energy'])
results_dict['lx'] = uc.set_in_units(lx, lammps_units['length'])
results_dict['ly'] = uc.set_in_units(ly, lammps_units['length'])
results_dict['lz'] = uc.set_in_units(lz, lammps_units['length'])
results_dict['xy'] = uc.set_in_units(xy, lammps_units['length'])
results_dict['xz'] = uc.set_in_units(xz, lammps_units['length'])
results_dict['yz'] = uc.set_in_units(yz, lammps_units['length'])
results_dict['measured_pxx'] = uc.set_in_units(thermo.Pxx.values[-1],
lammps_units['pressure'])
results_dict['measured_pyy'] = uc.set_in_units(thermo.Pyy.values[-1],
lammps_units['pressure'])
results_dict['measured_pzz'] = uc.set_in_units(thermo.Pzz.values[-1],
lammps_units['pressure'])
results_dict['measured_pxy'] = uc.set_in_units(thermo.Pxy.values[-1],
lammps_units['pressure'])
results_dict['measured_pxz'] = uc.set_in_units(thermo.Pxz.values[-1],
lammps_units['pressure'])
results_dict['measured_pyz'] = uc.set_in_units(thermo.Pyz.values[-1],
lammps_units['pressure'])
return results_dict
def relax_box(lammps_command,
system,
potential,
mpi_command=None,
strainrange=1e-6,
p_xx=0.0,
p_yy=0.0,
p_zz=0.0,
p_xy=0.0,
p_xz=0.0,
p_yz=0.0,
tol=1e-10,
diverge_scale=3.):
"""
Quickly refines static orthorhombic system by evaluating the elastic
constants and the virial pressure.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
strainrange : float, optional
The small strain value to apply when calculating the elastic
constants (default is 1e-6).
p_xx : float, optional
The value to relax the x tensile pressure component to (default is
0.0).
p_yy : float, optional
The value to relax the y tensile pressure component to (default is
0.0).
p_zz : float, optional
The value to relax the z tensile pressure component to (default is
0.0).
tol : float, optional
The relative tolerance used to determine if the lattice constants have
converged (default is 1e-10).
diverge_scale : float, optional
Factor to identify if the system's dimensions have diverged. Divergence
is identified if either any current box dimension is greater than the
original dimension multiplied by diverge_scale, or if any current box
dimension is less than the original dimension divided by diverge_scale.
(Default is 3.0).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'a_lat'** (*float*) - The relaxed a lattice constant.
- **'b_lat'** (*float*) - The relaxed b lattice constant.
- **'c_lat'** (*float*) - The relaxed c lattice constant.
- **'alpha_lat'** (*float*) - The alpha lattice angle.
- **'beta_lat'** (*float*) - The beta lattice angle.
- **'gamma_lat'** (*float*) - The gamma lattice angle.
- **'E_coh'** (*float*) - The cohesive energy of the relaxed system.
- **'stress'** (*numpy.array*) - The measured stress state of the
relaxed system.
- **'C_elastic'** (*atomman.ElasticConstants*) - The relaxed system's
elastic constants.
- **'system_relaxed'** (*atomman.System*) - The relaxed system.
Raises
------
RuntimeError
If system diverges or no convergence reached after 100 cycles.
"""
# Flag for if values have converged
converged = False
# Define current and old systems
system_current = deepcopy(system)
system_old = None
system.dump('atom_dump', f='initial.dump')
for cycle in range(100):
# Run LAMMPS and evaluate results based on system_old
results = calc_cij(lammps_command,
system_current,
potential,
mpi_command=mpi_command,
p_xx=p_xx,
p_yy=p_yy,
p_zz=p_zz,
strainrange=strainrange,
cycle=cycle)
system_new = results['system_new']
# Compare new and current to test for convergence
if np.allclose(system_new.box.vects,
system_current.box.vects,
rtol=tol,
atol=0):
converged = True
break
# Compare old and new to test for double-value convergence
elif system_old is not None and np.allclose(
system_new.box.vects, system_old.box.vects, rtol=tol, atol=0):
# Update current to average of old and new
system_current.box_set(
a=(system_new.box.a + system_old.box.a) / 2.,
b=(system_new.box.b + system_old.box.b) / 2.,
c=(system_new.box.c + system_old.box.c) / 2.,
scale=True)
# Calculate Cij for the averaged system
results = calc_cij(lammps_command,
system_current,
potential,
mpi_command=mpi_command,
p_xx=p_xx,
p_yy=p_yy,
p_zz=p_zz,
strainrange=strainrange,
cycle=cycle + 1)
system_new = results['system_new']
converged = True
break
# Test for divergence
elif system_new.box.a < system.box.a / diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif system_new.box.a > system.box.a * diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif system_new.box.b < system.box.b / diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif system_new.box.b > system.box.b * diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif system_new.box.c < system.box.c / diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif system_new.box.c > system.box.c * diverge_scale:
raise RuntimeError('Divergence of box dimensions')
elif results['E_coh'] == 0.0:
raise RuntimeError('Divergence: cohesive energy is 0')
# If not converged or diverged, current -> old and new -> current
else:
system_old, system_current = system_current, system_new
# Return values when converged
if converged:
system_new.dump('atom_dump', f='final.dump')
# Build results_dict
results_dict = {}
results_dict['dumpfile_initial'] = 'initial.dump'
results_dict['symbols_initial'] = system.symbols
results_dict['dumpfile_final'] = 'final.dump'
results_dict['symbols_final'] = system.symbols
results_dict['lx'] = system_new.box.lx
results_dict['ly'] = system_new.box.ly
results_dict['lz'] = system_new.box.lz
results_dict['xy'] = system_new.box.xy
results_dict['xz'] = system_new.box.xz
results_dict['yz'] = system_new.box.yz
results_dict['E_coh'] = results['E_coh']
results_dict['measured_pxx'] = results['measured_pxx']
results_dict['measured_pyy'] = results['measured_pyy']
results_dict['measured_pzz'] = results['measured_pzz']
results_dict['measured_pxy'] = results['measured_pxy']
results_dict['measured_pxz'] = results['measured_pxz']
results_dict['measured_pyz'] = results['measured_pyz']
return results_dict
else:
raise RuntimeError('Failed to converge after 100 cycles')
def calc_cij(lammps_command,
system,
potential,
mpi_command=None,
p_xx=0.0,
p_yy=0.0,
p_zz=0.0,
strainrange=1e-6,
cycle=0):
"""
Runs cij.in LAMMPS script to evaluate Cij, and E_coh of the current system,
and define a new system with updated box dimensions to test.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
strainrange : float, optional
The small strain value to apply when calculating the elastic
constants (default is 1e-6).
p_xx : float, optional
The value to relax the x tensile pressure component to (default is
0.0).
p_yy : float, optional
The value to relax the y tensile pressure component to (default is
0.0).
p_zz : float, optional
The value to relax the z tensile pressure component to (default is
0.0).
cycle : int, optional
Indicates the iteration cycle of quick_a_Cij(). This is used to
uniquely save the LAMMPS input and output files.
Returns
-------
dict
Dictionary of results consisting of keys:
- **'E_coh'** (*float*) - The cohesive energy of the supplied system.
- **'stress'** (*numpy.array*) - The measured stress state of the
supplied system.
- **'C_elastic'** (*atomman.ElasticConstants*) - The supplied system's
elastic constants.
- **'system_new'** (*atomman.System*) - System with updated box
dimensions.
Raises
------
RuntimeError
If any of the new box dimensions are less than zero.
"""
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data',
f='init' + str(cycle) + '.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(system.symbols)
lammps_variables['delta'] = strainrange
lammps_variables['steps'] = 2
# Write lammps input script
template_file = 'cij.template'
lammps_script = 'cij.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run lammps
output = lmp.run(lammps_command,
lammps_script,
mpi_command=mpi_command,
return_style='model')
shutil.move('log.lammps', 'cij-' + str(cycle) + '-log.lammps')
# Extract LAMMPS thermo data. Each term ranges i=0-12 where i=0 is undeformed
# The remaining values are for -/+ strain pairs in the six unique directions
lx = uc.set_in_units(np.array(output.finds('Lx')), lammps_units['length'])
ly = uc.set_in_units(np.array(output.finds('Ly')), lammps_units['length'])
lz = uc.set_in_units(np.array(output.finds('Lz')), lammps_units['length'])
xy = uc.set_in_units(np.array(output.finds('Xy')), lammps_units['length'])
xz = uc.set_in_units(np.array(output.finds('Xz')), lammps_units['length'])
yz = uc.set_in_units(np.array(output.finds('Yz')), lammps_units['length'])
pxx = uc.set_in_units(np.array(output.finds('Pxx')),
lammps_units['pressure'])
pyy = uc.set_in_units(np.array(output.finds('Pyy')),
lammps_units['pressure'])
pzz = uc.set_in_units(np.array(output.finds('Pzz')),
lammps_units['pressure'])
pxy = uc.set_in_units(np.array(output.finds('Pxy')),
lammps_units['pressure'])
pxz = uc.set_in_units(np.array(output.finds('Pxz')),
lammps_units['pressure'])
pyz = uc.set_in_units(np.array(output.finds('Pyz')),
lammps_units['pressure'])
pe = uc.set_in_units(
np.array(output.finds('PotEng')) / system.natoms,
lammps_units['energy'])
# Set the six non-zero strain values
strains = np.array([(lx[2] - lx[1]) / lx[0], (ly[4] - ly[3]) / ly[0],
(lz[6] - lz[5]) / lz[0], (yz[8] - yz[7]) / lz[0],
(xz[10] - xz[9]) / lz[0], (xy[12] - xy[11]) / ly[0]])
# Calculate cij using stress changes associated with each non-zero strain
cij = np.empty((6, 6))
for i in range(6):
delta_stress = np.array([
pxx[2 * i + 1] - pxx[2 * i + 2], pyy[2 * i + 1] - pyy[2 * i + 2],
pzz[2 * i + 1] - pzz[2 * i + 2], pyz[2 * i + 1] - pyz[2 * i + 2],
pxz[2 * i + 1] - pxz[2 * i + 2], pxy[2 * i + 1] - pxy[2 * i + 2]
])
cij[i] = delta_stress / strains[i]
for i in range(6):
for j in range(i):
cij[i, j] = cij[j, i] = (cij[i, j] + cij[j, i]) / 2
C = am.ElasticConstants(Cij=cij)
S = C.Sij
# Extract the current stress state
stress = -1 * np.array([[pxx[0], pxy[0], pxz[0]], [pxy[0], pyy[0], pyz[0]],
[pxz[0], pyz[0], pzz[0]]])
s_xx = stress[0, 0] + p_xx
s_yy = stress[1, 1] + p_yy
s_zz = stress[2, 2] + p_zz
new_a = system.box.a / (S[0, 0] * s_xx + S[0, 1] * s_yy + S[0, 2] * s_zz +
1)
new_b = system.box.b / (S[1, 0] * s_xx + S[1, 1] * s_yy + S[1, 2] * s_zz +
1)
new_c = system.box.c / (S[2, 0] * s_xx + S[2, 1] * s_yy + S[2, 2] * s_zz +
1)
if new_a <= 0 or new_b <= 0 or new_c <= 0:
raise RuntimeError('Divergence of box dimensions to <= 0')
system_new = deepcopy(system)
system_new.box_set(a=new_a, b=new_b, c=new_c, scale=True)
results_dict = {}
results_dict['E_coh'] = pe[0]
results_dict['system_new'] = system_new
results_dict['measured_pxx'] = pxx[0]
results_dict['measured_pyy'] = pyy[0]
results_dict['measured_pzz'] = pzz[0]
results_dict['measured_pxy'] = pxy[0]
results_dict['measured_pxz'] = pxz[0]
results_dict['measured_pyz'] = pyz[0]
return results_dict
def elastic_constants_static(lammps_command, system, potential, mpi_command=None,
strainrange=1e-6, etol=0.0, ftol=0.0, maxiter=10000,
maxeval=100000, dmax=uc.set_in_units(0.01, 'angstrom')):
"""
Repeatedly runs the ELASTIC example distributed with LAMMPS until box
dimensions converge within a tolerance.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
strainrange : float, optional
The small strain value to apply when calculating the elastic
constants (default is 1e-6).
etol : float, optional
The energy tolerance for the structure minimization. This value is
unitless. (Default is 0.0).
ftol : float, optional
The force tolerance for the structure minimization. This value is in
units of force. (Default is 0.0).
maxiter : int, optional
The maximum number of minimization iterations to use (default is 10000).
maxeval : int, optional
The maximum number of minimization evaluations to use (default is
100000).
dmax : float, optional
The maximum distance in length units that any atom is allowed to relax
in any direction during a single minimization iteration (default is
0.01 Angstroms).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'a_lat'** (*float*) - The relaxed a lattice constant.
- **'b_lat'** (*float*) - The relaxed b lattice constant.
- **'c_lat'** (*float*) - The relaxed c lattice constant.
- **'alpha_lat'** (*float*) - The alpha lattice angle.
- **'beta_lat'** (*float*) - The beta lattice angle.
- **'gamma_lat'** (*float*) - The gamma lattice angle.
- **'E_coh'** (*float*) - The cohesive energy of the relaxed system.
- **'stress'** (*numpy.array*) - The measured stress state of the
relaxed system.
- **'C_elastic'** (*atomman.ElasticConstants*) - The relaxed system's
elastic constants.
- **'system_relaxed'** (*atomman.System*) - The relaxed system.
"""
# Convert hexagonal cells to orthorhombic to avoid LAMMPS tilt issues
if am.tools.ishexagonal(system.box):
system = system.rotate([[2,-1,-1,0], [0, 1, -1, 0], [0,0,0,1]])
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Get lammps version date
lammps_date = lmp.checkversion(lammps_command)['date']
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data', f='init.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(system.symbols)
lammps_variables['strainrange'] = strainrange
lammps_variables['etol'] = etol
lammps_variables['ftol'] = uc.get_in_units(ftol, lammps_units['force'])
lammps_variables['maxiter'] = maxiter
lammps_variables['maxeval'] = maxeval
lammps_variables['dmax'] = uc.get_in_units(dmax, lammps_units['length'])
# Fill in template files
template_file = 'cij.template'
lammps_script = 'cij.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
template_file2 = 'potential.template'
lammps_script2 = 'potential.in'
with open(template_file2) as f:
template = f.read()
with open(lammps_script2, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run LAMMPS
output = lmp.run(lammps_command, lammps_script, mpi_command)
# Pull out initial state
thermo = output.simulations[0]['thermo']
pxx0 = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy0 = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz0 = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz0 = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz0 = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy0 = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Negative strains
cij_n = np.empty((6,6))
for i in range(6):
j = 1 + i * 2
# Pull out strained state
thermo = output.simulations[j]['thermo']
pxx = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Calculate cij_n using stress changes
cij_n[i] = np.array([pxx - pxx0, pyy - pyy0, pzz - pzz0,
pyz - pyz0, pxz - pxz0, pxy - pxy0])/ strainrange
# Positive strains
cij_p = np.empty((6,6))
for i in range(6):
j = 2 + i * 2
# Pull out strained state
thermo = output.simulations[j]['thermo']
pxx = uc.set_in_units(thermo.Pxx.values[-1], lammps_units['pressure'])
pyy = uc.set_in_units(thermo.Pyy.values[-1], lammps_units['pressure'])
pzz = uc.set_in_units(thermo.Pzz.values[-1], lammps_units['pressure'])
pyz = uc.set_in_units(thermo.Pyz.values[-1], lammps_units['pressure'])
pxz = uc.set_in_units(thermo.Pxz.values[-1], lammps_units['pressure'])
pxy = uc.set_in_units(thermo.Pxy.values[-1], lammps_units['pressure'])
# Calculate cij_p using stress changes
cij_p[i] = -np.array([pxx - pxx0, pyy - pyy0, pzz - pzz0,
pyz - pyz0, pxz - pxz0, pxy - pxy0])/ strainrange
# Average symmetric values
cij = (cij_n + cij_p) / 2
for i in range(6):
for j in range(i):
cij[i,j] = cij[j,i] = (cij[i,j] + cij[j,i]) / 2
# Define results_dict
results_dict = {}
results_dict['raw_cij_negative'] = cij_n
results_dict['raw_cij_positive'] = cij_p
results_dict['C'] = am.ElasticConstants(Cij=cij)
return results_dict
def e_vs_r(lammps_command, system, potential,
mpi_command=None, ucell=None,
rmin=uc.set_in_units(2.0, 'angstrom'),
rmax=uc.set_in_units(6.0, 'angstrom'), rsteps=200):
"""
Performs a cohesive energy scan over a range of interatomic spaces, r.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
ucell : atomman.System, optional
The fundamental unit cell correspodning to system. This is used to
convert system dimensions to cell dimensions. If not given, ucell will
be taken as system.
rmin : float, optional
The minimum r spacing to use (default value is 2.0 angstroms).
rmax : float, optional
The maximum r spacing to use (default value is 6.0 angstroms).
rsteps : int, optional
The number of r spacing steps to evaluate (default value is 200).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'r_values'** (*numpy.array of float*) - All interatomic spacings,
r, explored.
- **'a_values'** (*numpy.array of float*) - All unit cell a lattice
constants corresponding to the values explored.
- **'Ecoh_values'** (*numpy.array of float*) - The computed cohesive
energies for each r value.
- **'min_cell'** (*list of atomman.System*) - Systems corresponding to
the minima identified in the Ecoh_values.
"""
# Make system a deepcopy of itself (protect original from changes)
system = deepcopy(system)
# Set ucell = system if ucell not given
if ucell is None:
ucell = system
# Calculate the r/a ratio for the unit cell
r_a = r_a_ratio(ucell)
# Get ratios of lx, ly, and lz of system relative to a of ucell
lx_a = system.box.a / ucell.box.a
ly_a = system.box.b / ucell.box.a
lz_a = system.box.c / ucell.box.a
alpha = system.box.alpha
beta = system.box.beta
gamma = system.box.gamma
# Build lists of values
r_values = np.linspace(rmin, rmax, rsteps)
a_values = r_values / r_a
Ecoh_values = np.empty(rsteps)
# Loop over values
for i in range(rsteps):
# Rescale system's box
a = a_values[i]
system.box_set(a = a * lx_a,
b = a * ly_a,
c = a * lz_a,
alpha=alpha, beta=beta, gamma=gamma, scale=True)
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data', f='atom.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(system.symbols)
# Write lammps input script
template_file = 'run0.template'
lammps_script = 'run0.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(iprPy.tools.filltemplate(template, lammps_variables,
'<', '>'))
# Run lammps and extract data
output = lmp.run(lammps_command, lammps_script, mpi_command)
thermo = output.simulations[0]['thermo']
if output.lammps_date < datetime.date(2016, 8, 1):
Ecoh_values[i] = uc.set_in_units(thermo.peatom.values[-1],
lammps_units['energy'])
else:
Ecoh_values[i] = uc.set_in_units(thermo.v_peatom.values[-1],
lammps_units['energy'])
# Rename log.lammps
shutil.move('log.lammps', 'run0-'+str(i)+'-log.lammps')
# Find unit cell systems at the energy minimums
min_cells = []
for i in range(1, rsteps - 1):
if (Ecoh_values[i] < Ecoh_values[i-1]
and Ecoh_values[i] < Ecoh_values[i+1]):
a = a_values[i]
cell = deepcopy(ucell)
cell.box_set(a = a,
b = a * ucell.box.b / ucell.box.a,
c = a * ucell.box.c / ucell.box.a,
alpha=alpha, beta=beta, gamma=gamma, scale=True)
min_cells.append(cell)
# Collect results
results_dict = {}
results_dict['r_values'] = r_values
results_dict['a_values'] = a_values
results_dict['Ecoh_values'] = Ecoh_values
results_dict['min_cell'] = min_cells
return results_dict
def e_vs_r(lammps_command,
system,
potential,
mpi_command=None,
ucell=None,
rmin=uc.set_in_units(2.0, 'angstrom'),
rmax=uc.set_in_units(6.0, 'angstrom'),
rsteps=200):
"""
Performs a cohesive energy scan over a range of interatomic spaces, r.
Parameters
----------
lammps_command :str
Command for running LAMMPS.
system : atomman.System
The system to perform the calculation on.
potential : atomman.lammps.Potential
The LAMMPS implemented potential to use.
mpi_command : str, optional
The MPI command for running LAMMPS in parallel. If not given, LAMMPS
will run serially.
ucell : atomman.System, optional
The fundamental unit cell correspodning to system. This is used to
convert system dimensions to cell dimensions. If not given, ucell will
be taken as system.
rmin : float, optional
The minimum r spacing to use (default value is 2.0 angstroms).
rmax : float, optional
The maximum r spacing to use (default value is 6.0 angstroms).
rsteps : int, optional
The number of r spacing steps to evaluate (default value is 200).
Returns
-------
dict
Dictionary of results consisting of keys:
- **'r_values'** (*numpy.array of float*) - All interatomic spacings,
r, explored.
- **'a_values'** (*numpy.array of float*) - All unit cell a lattice
constants corresponding to the values explored.
- **'Ecoh_values'** (*numpy.array of float*) - The computed cohesive
energies for each r value.
- **'min_cell'** (*list of atomman.System*) - Systems corresponding to
the minima identified in the Ecoh_values.
"""
# Make system a deepcopy of itself (protect original from changes)
system = deepcopy(system)
# Set ucell = system if ucell not given
if ucell is None:
ucell = system
# Calculate the r/a ratio for the unit cell
r_a = r_a_ratio(ucell)
# Get ratios of lx, ly, and lz of system relative to a of ucell
lx_a = system.box.a / ucell.box.a
ly_a = system.box.b / ucell.box.a
lz_a = system.box.c / ucell.box.a
alpha = system.box.alpha
beta = system.box.beta
gamma = system.box.gamma
# Build lists of values
r_values = np.linspace(rmin, rmax, rsteps)
a_values = r_values / r_a
Ecoh_values = np.empty(rsteps)
# Loop over values
for i in range(rsteps):
# Rescale system's box
a = a_values[i]
system.box_set(a=a * lx_a,
b=a * ly_a,
c=a * lz_a,
alpha=alpha,
beta=beta,
gamma=gamma,
scale=True)
# Get lammps units
lammps_units = lmp.style.unit(potential.units)
# Define lammps variables
lammps_variables = {}
system_info = system.dump('atom_data',
f='atom.dat',
units=potential.units,
atom_style=potential.atom_style)
lammps_variables['atomman_system_info'] = system_info
lammps_variables['atomman_pair_info'] = potential.pair_info(
system.symbols)
# Write lammps input script
template_file = 'run0.template'
lammps_script = 'run0.in'
with open(template_file) as f:
template = f.read()
with open(lammps_script, 'w') as f:
f.write(
iprPy.tools.filltemplate(template, lammps_variables, '<', '>'))
# Run lammps and extract data
output = lmp.run(lammps_command, lammps_script, mpi_command)
thermo = output.simulations[0]['thermo']
if output.lammps_date < datetime.date(2016, 8, 1):
Ecoh_values[i] = uc.set_in_units(thermo.peatom.values[-1],
lammps_units['energy'])
else:
Ecoh_values[i] = uc.set_in_units(thermo.v_peatom.values[-1],
lammps_units['energy'])
# Rename log.lammps
shutil.move('log.lammps', 'run0-' + str(i) + '-log.lammps')
# Find unit cell systems at the energy minimums
min_cells = []
for i in range(1, rsteps - 1):
if (Ecoh_values[i] < Ecoh_values[i - 1]
and Ecoh_values[i] < Ecoh_values[i + 1]):
a = a_values[i]
cell = deepcopy(ucell)
cell.box_set(a=a,
b=a * ucell.box.b / ucell.box.a,
c=a * ucell.box.c / ucell.box.a,
alpha=alpha,
beta=beta,
gamma=gamma,
scale=True)
min_cells.append(cell)
# Collect results
results_dict = {}
results_dict['r_values'] = r_values
results_dict['a_values'] = a_values
results_dict['Ecoh_values'] = Ecoh_values
results_dict['min_cell'] = min_cells
return results_dict