def test_msd_global_temp(self):
"""Tests diffusion via MSD for global gamma and temperature"""
gamma = 9.4
kT = 0.37
dt = 0.5
system = self.system
system.part.clear()
p = system.part.add(pos=(0, 0, 0), id=0)
system.time_step = dt
system.thermostat.set_brownian(kT=kT, gamma=gamma, seed=42)
system.cell_system.skin = 0.4
pos_obs = ParticlePositions(ids=(p.id, ))
c_pos = Correlator(obs1=pos_obs,
tau_lin=16,
tau_max=100.,
delta_N=10,
corr_operation="square_distance_componentwise",
compress1="discard1")
system.auto_update_accumulators.add(c_pos)
system.integrator.run(500000)
c_pos.finalize()
# Check MSD
msd = c_pos.result()
system.auto_update_accumulators.clear()
def expected_msd(x):
return 2. * kT / gamma * x
for i in range(2, 6):
np.testing.assert_allclose(msd[i, 2:5],
expected_msd(msd[i, 0]),
rtol=0.02)
def test_06__diffusion(self):
"""This tests rotational and translational diffusion coeff via Green-Kubo"""
system = self.system
system.part.clear()
kT = 1.37
dt = 0.1
system.time_step = dt
# Translational gamma. We cannot test per-component, if rotation is on,
# because body and space frames become different.
gamma = 3.1
# Rotational gamma
gamma_rot_i = 4.7
gamma_rot_a = [4.2, 1, 1.2]
# If we have langevin per particle:
# per particle kT
per_part_kT = 1.6
# Translation
per_part_gamma = 1.63
# Rotational
per_part_gamma_rot_i = 2.6
per_part_gamma_rot_a = [2.4, 3.8, 1.1]
# Particle with global thermostat params
p_global = system.part.add(pos=(0, 0, 0))
# Make sure, mass doesn't change diff coeff
self.setup_diff_mass_rinertia(p_global)
# particle specific gamma, kT, and both
if espressomd.has_features("LANGEVIN_PER_PARTICLE"):
p_gamma = system.part.add(pos=(0, 0, 0))
self.setup_diff_mass_rinertia(p_gamma)
if espressomd.has_features("PARTICLE_ANISOTROPY"):
p_gamma.gamma = per_part_gamma, per_part_gamma, per_part_gamma
if espressomd.has_features("ROTATION"):
p_gamma.gamma_rot = per_part_gamma_rot_a
else:
p_gamma.gamma = per_part_gamma
if espressomd.has_features("ROTATION"):
p_gamma.gamma_rot = per_part_gamma_rot_i
p_kT = system.part.add(pos=(0, 0, 0))
self.setup_diff_mass_rinertia(p_kT)
p_kT.temp = per_part_kT
p_both = system.part.add(pos=(0, 0, 0))
self.setup_diff_mass_rinertia(p_both)
p_both.temp = per_part_kT
if espressomd.has_features("PARTICLE_ANISOTROPY"):
p_both.gamma = per_part_gamma, per_part_gamma, per_part_gamma
if espressomd.has_features("ROTATION"):
p_both.gamma_rot = per_part_gamma_rot_a
else:
p_both.gamma = per_part_gamma
if espressomd.has_features("ROTATION"):
p_both.gamma_rot = per_part_gamma_rot_i
# Thermostat setup
if espressomd.has_features("ROTATION"):
if espressomd.has_features("PARTICLE_ANISOTROPY"):
# particle anisotropy and rotation
system.thermostat.set_langevin(kT=kT,
gamma=gamma,
gamma_rotation=gamma_rot_a,
seed=41)
else:
# Rotation without particle anisotropy
system.thermostat.set_langevin(kT=kT,
gamma=gamma,
gamma_rotation=gamma_rot_i,
seed=41)
else:
# No rotation
system.thermostat.set_langevin(kT=kT, gamma=gamma, seed=41)
system.cell_system.skin = 0.4
system.integrator.run(100)
# Correlators
vel_obs = {}
omega_obs = {}
corr_vel = {}
corr_omega = {}
all_particles = [p_global]
if espressomd.has_features("LANGEVIN_PER_PARTICLE"):
all_particles.append(p_gamma)
all_particles.append(p_kT)
all_particles.append(p_both)
# linear vel
vel_obs = ParticleVelocities(ids=system.part[:].id)
corr_vel = Correlator(obs1=vel_obs,
tau_lin=10,
tau_max=1.4,
delta_N=2,
corr_operation="componentwise_product",
compress1="discard1")
system.auto_update_accumulators.add(corr_vel)
# angular vel
if espressomd.has_features("ROTATION"):
omega_obs = ParticleBodyAngularVelocities(ids=system.part[:].id)
corr_omega = Correlator(obs1=omega_obs,
tau_lin=10,
tau_max=1.5,
delta_N=2,
corr_operation="componentwise_product",
compress1="discard1")
system.auto_update_accumulators.add(corr_omega)
system.integrator.run(80000)
system.auto_update_accumulators.remove(corr_vel)
corr_vel.finalize()
if espressomd.has_features("ROTATION"):
system.auto_update_accumulators.remove(corr_omega)
corr_omega.finalize()
# Verify diffusion
# Translation
# Cast gammas to vector, to make checks independent of
# PARTICLE_ANISOTROPY
gamma = np.ones(3) * gamma
per_part_gamma = np.ones(3) * per_part_gamma
self.verify_diffusion(p_global, corr_vel, kT, gamma)
if espressomd.has_features("LANGEVIN_PER_PARTICLE"):
self.verify_diffusion(p_gamma, corr_vel, kT, per_part_gamma)
self.verify_diffusion(p_kT, corr_vel, per_part_kT, gamma)
self.verify_diffusion(p_both, corr_vel, per_part_kT,
per_part_gamma)
# Rotation
if espressomd.has_features("ROTATION"):
# Decide on effective gamma rotation, since for rotation it is
# direction dependent
eff_gamma_rot = None
per_part_eff_gamma_rot = None
if espressomd.has_features("PARTICLE_ANISOTROPY"):
eff_gamma_rot = gamma_rot_a
eff_per_part_gamma_rot = per_part_gamma_rot_a
else:
eff_gamma_rot = gamma_rot_i * np.ones(3)
eff_per_part_gamma_rot = per_part_gamma_rot_i * np.ones(3)
self.verify_diffusion(p_global, corr_omega, kT, eff_gamma_rot)
if espressomd.has_features("LANGEVIN_PER_PARTICLE"):
self.verify_diffusion(p_gamma, corr_omega, kT,
eff_per_part_gamma_rot)
self.verify_diffusion(p_kT, corr_omega, per_part_kT,
eff_gamma_rot)
self.verify_diffusion(p_both, corr_omega, per_part_kT,
eff_per_part_gamma_rot)
system.set_random_state_PRNG()
#system.seed = system.cell_system.get_state()['n_nodes'] * [1234]
np.random.seed(seed=system.seed)
p = system.part.add(pos=(0, 0, 0), id=0)
system.time_step = dt
system.thermostat.set_langevin(kT=kT, gamma=gamma, seed=42)
system.cell_system.skin = 0.4
system.integrator.run(1000)
pos_obs = ParticlePositions(ids=(0, ))
vel_obs = ParticleVelocities(ids=(0, ))
c_pos = Correlator(obs1=pos_obs,
tau_lin=16,
tau_max=100.,
delta_N=10,
corr_operation="square_distance_componentwise",
compress1="discard1")
c_vel = Correlator(obs1=vel_obs,
tau_lin=16,
tau_max=20.,
delta_N=1,
corr_operation="scalar_product",
compress1="discard1")
system.auto_update_accumulators.add(c_pos)
system.auto_update_accumulators.add(c_vel)
system.integrator.run(1000000)
c_pos.finalize()
c_vel.finalize()
# Place a single active particle that can rotate in all 3 dimensions.
# Set mass and rotational inertia to separate the timescales for
# translational and rotational diffusion.
system.part.add(pos=[5.0, 5.0, 5.0],
swimming={'v_swim': vel},
mass=0.1,
rotation=3 * [True],
rinertia=3 * [1.])
# Initialize the mean squared displacement (MSD) correlator
tmax = system.time_step * SAMP_STEPS
pos_id = ParticlePositions(ids=[0])
msd = Correlator(obs1=pos_id,
corr_operation="square_distance_componentwise",
delta_N=1,
tau_max=tmax,
tau_lin=16)
system.auto_update_accumulators.add(msd)
# Initialize the velocity auto-correlation function (VACF) correlator
vel_id = ParticleVelocities(ids=[0])
vacf = Correlator(obs1=vel_id,
corr_operation="scalar_product",
delta_N=1,
tau_max=tmax,
tau_lin=16)
system.auto_update_accumulators.add(vacf)
# Initialize the angular velocity auto-correlation function (AVACF)
# correlator
def calc(var):
# AVB: Create an output directory for this to store the output files
outdir = "./Noelle/r01.5kBT4Ads/1000=3.2"
if not os.path.exists(outdir):
os.makedirs(outdir)
# Setup constant
time_step = 0.01
loops = 30
step_per_loop = 100
# AVB: the parameters (that I usually use)
a = 0.05
r0 = 2.0 * a
kBT = 4.0e-6
vwf_type = 0
collagen_type = 1
monomer_mass = 0.01
box_l = 32.0
#print("Shear velocity:")
#shear_velocity = float(input())
#vy = box_l*shear_velocity
vy = var
print(vy)
v = [0, vy, 0]
# System setup
system = 0
system = System(box_l=[box_l, box_l, box_l])
system.set_random_state_PRNG()
np.random.seed(seed=system.seed)
system.cell_system.skin = 0.4
mpc = 20 # The number of monomers has been set to be 20 as default
# Change this value for further simulations
# Fene interaction
fene = interactions.FeneBond(k=0.04, d_r_max=0.3)
system.bonded_inter.add(fene)
# Setup polymer of part_id 0 with fene bond
# AVB: Notice the mode, max_tries and shield parameters for pruned self-avoiding random walk algorithm
polymer.create_polymer(N_P=1,
MPC=mpc,
bond=fene,
bond_length=r0,
start_pos=[29.8, 16.0, 16.0],
mode=2,
max_tries=100,
shield=0.6 * r0)
# AVB: setting the type of particles and changing mass of each monomer to 0.01
system.part[:].type = vwf_type
system.part[:].mass = monomer_mass
# AVB: I suggest to add Lennard-Jones interaction between the monomers
# AVB: to reproduce hydrophobicity
# AVB: parameters for the potential (amplitude and cut-off redius)
amplVwfVwf = 4.0 * kBT # sometimes we change this to 2.0*kBT
rcutVwfVwf = 1.5 * r0
# AVB: the potential
system.non_bonded_inter[vwf_type, vwf_type].lennard_jones.set_params(
epsilon=amplVwfVwf,
sigma=r0 / 1.122,
shift="auto",
cutoff=rcutVwfVwf,
min=r0 * 0.6)
print("Warming up the polymer chain.")
## For longer chains (>100) an extensive
## warmup is neccessary ...
system.time_step = 0.002
system.thermostat.set_langevin(kT=4.0e-6, gamma=1.0)
# AVB: Here the Langevin thermostat is needed, because we have not yet initialized the LB-fluid.
# AVB: And somehow it is necessary so that the polymer adopts the equilibrium conformation of the globule.
# AVB: you may skip this step
for i in range(100):
system.force_cap = float(i) + 1
system.integrator.run(100)
print("Warmup finished.")
system.force_cap = 0
system.integrator.run(100)
system.time_step = time_step
system.integrator.run(500)
# AVB: the following command turns the Langevin thermostat on in line 49
system.thermostat.turn_off()
# AVB: This command sets the velocities of all particles to zero
system.part[:].v = [0, 0, 0]
# AVB: The density was too small here. I have set 1.0 for now.
# AVB: It would be necessary to recalculate, but the density of the liquid should not affect the movements of the polymer (this is how our physical model works).
lbf = espressomd.lb.LBFluid(agrid=1,
dens=1.0,
visc=1.0e2,
tau=time_step,
fric=0.01)
system.actors.add(lbf)
system.thermostat.set_lb(kT=4.0e-6)
# Setup boundaries
walls = [lbboundaries.LBBoundary() for k in range(2)]
walls[0].set_params(shape=shapes.Wall(normal=[1, 0, 0], dist=1.5),
velocity=v)
walls[1].set_params(shape=shapes.Wall(normal=[-1, 0, 0], dist=-30.5))
for wall in walls:
system.lbboundaries.add(wall)
print("Warming up the system with LB fluid.")
system.integrator.run(5000)
print("LB fluid warming finished.")
# AVB: after this you should have a completely collapsed polymer globule
# AVB: If you want to watch the process of globule formation in Paraview, just change 5000 to 0 in line 100
N = 25
x_coord = np.array([30] * N)
y_coord = np.arange(14, 24, 5 / N)
z_coord = np.arange(14, 24, 5 / N)
for i in range(N):
for j in range(N):
system.part.add(id=i * N + j + 100,
pos=np.array([x_coord[i], y_coord[j], z_coord[i]]),
v=np.array([0, 0, 0]),
type=i * N + j + 100)
all_collagen = range(100, (N - 1) * N + (N - 1) + 100)
system.comfixed.types = all_collagen
for i in range(100, (N - 1) * N + (N - 1) + 100):
system.non_bonded_inter[vwf_type,
i].lennard_jones.set_params(epsilon=amplVwfVwf,
sigma=r0 / 1.122,
shift="auto",
cutoff=rcutVwfVwf,
min=r0 * 0.6)
# configure correlators
com_pos = ComPosition(ids=(0, ))
c = Correlator(obs1=com_pos,
tau_lin=16,
tau_max=loops * step_per_loop,
delta_N=1,
corr_operation="square_distance_componentwise",
compress1="discard1")
system.auto_update_accumulators.add(c)
print("Sampling started.")
print("lenth after warmup")
print(
system.analysis.calc_re(chain_start=0,
number_of_chains=1,
chain_length=mpc - 1)[0])
lengths = []
ylengths = []
for i in range(loops):
system.integrator.run(step_per_loop)
system.analysis.append()
lengths.append(
system.analysis.calc_re(chain_start=0,
number_of_chains=1,
chain_length=mpc - 1)[0])
lbf.print_vtk_velocity(outdir + "/" + str(vy) + "%04i.vtk" % i)
system.part.writevtk(outdir + "/" + str(vy) + "vwf_all%04i.vtk" % i,
types=all_collagen)
system.part.writevtk(outdir + "/" + str(vy) + "vwf_poly%04i.vtk" % i,
types=[0])
cor = list(system.part[:].pos)
y = []
for l in cor:
y.append(l[1])
ylengths.append(max(y) - min(y))
sys.stdout.write("\rSampling: %05i" % i)
sys.stdout.flush()
walls[0].set_params(shape=shapes.Wall(normal=[1, 0, 0], dist=1.5))
walls[1].set_params(shape=shapes.Wall(normal=[-1, 0, 0], dist=-30.5))
for i in range(100):
system.integrator.run(step_per_loop)
lengths.append(
system.analysis.calc_re(chain_start=0,
number_of_chains=1,
chain_length=mpc - 1)[0])
system.part.writevtk(outdir + "/" + str(vy) +
"vwf_all[r0=2,kBT=4]intheEND.vtk")
with open(outdir + "/lengths" + str(vy) + ".dat", "a") as datafile:
datafile.write("\n".join(map(str, lengths)))
with open(outdir + "/lengthsY" + str(vy) + ".dat", "a") as datafile:
datafile.write("\n".join(map(str, ylengths)))
mean_vy = [(vy * 10000) / 32, sum(ylengths) / len(ylengths)]
print("mean_vy")
print(mean_vy)
with open(outdir + "/mean_vy" + "2kBT_2r0" + ".dat", "a") as datafile:
datafile.write(" ".join(map(str, mean_vy)))
c.finalize()
corrdata = c.result()
corr = zeros((corrdata.shape[0], 2))
corr[:, 0] = corrdata[:, 0]
corr[:, 1] = (corrdata[:, 2] + corrdata[:, 3] + corrdata[:, 4]) / 3
savetxt(outdir + "/msd_nom" + str(mpc) + ".dat", corr)
with open(outdir + "/rh_out.dat", "a") as datafile:
rh = system.analysis.calc_rh(chain_start=0,
number_of_chains=1,
chain_length=mpc - 1)
datafile.write(str(mpc) + " " + str(rh[0]) + "\n")
system.thermostat.set_langevin(kT=1.0, gamma=1.0, seed=42)
# Place a single active particle (that can rotate freely! rotation=[1,1,1])
system.part.add(pos=[5.0, 5.0, 5.0], swimming={
'v_swim': vel}, rotation=[1, 1, 1])
# Initialize the mean squared displacement (MSD) correlator
tmax = tstep * sampsteps
pos_id = ParticlePositions(ids=[0])
msd = Correlator(obs1=pos_id,
corr_operation="square_distance_componentwise",
delta_N=1,
tau_max=tmax,
tau_lin=16)
system.auto_update_accumulators.add(msd)
## Exercise 3 ##
# Construct the auto-accumulators for the VACF and AVACF,
# using the example of the MSD
# Initialize the velocity auto-correlation function (VACF) correlator
...
# Initialize the angular velocity auto-correlation function (AVACF)
# correlator
# Place a single active particle that can rotate in all 3 dimensions.
# Set mass and rotational inertia to separate the timescales for
# translational and rotational diffusion.
system.part.add(pos=[5.0, 5.0, 5.0],
swimming={'v_swim': vel},
mass=0.1,
rotation=3 * [True],
rinertia=3 * [1.])
# Initialize the mean squared displacement (MSD) correlator
tmax = system.time_step * SAMP_STEPS
pos_id = ParticlePositions(ids=[0])
msd = Correlator(obs1=pos_id,
corr_operation="square_distance_componentwise",
delta_N=1,
tau_max=tmax,
tau_lin=16)
system.auto_update_accumulators.add(msd)
# Initialize the velocity auto-correlation function (VACF) correlator
vel_id = ParticleVelocities(ids=[0])
vacf = Correlator(obs1=vel_id,
corr_operation="scalar_product",
delta_N=1,
tau_max=tmax,
tau_lin=16)
system.auto_update_accumulators.add(vacf)
# Initialize the angular velocity auto-correlation function (AVACF)
# correlator
system.non_bonded_inter[0, 0].hat.set_params(F_max=F_max, cutoff=r_cut)
# Warm up and equilibration
system.integrator.run(1000000)
# Reset COM movement
g = GalileiTransform()
g.galilei_transform()
# Set up of correlators to obtain stress autocorrelation functions
dso = espressomd.observables.DPDStress()
plain_old_stress = espressomd.observables.StressTensor()
c_dpd = Correlator(obs1=dso,
tau_lin=tau_lin,
tau_max=tau_max,
delta_N=1,
corr_operation="componentwise_product",
compress1="discard1")
c_old = Correlator(obs1=plain_old_stress,
tau_lin=tau_lin,
tau_max=tau_max,
delta_N=1,
corr_operation="componentwise_product",
compress1="discard1")
system.auto_update_accumulators.add(c_dpd)
system.auto_update_accumulators.add(c_old)
# Open txt-files to save non-correlated results
dpd_stress = open("dpd_stress.txt", "w")
old_stress = open("old_stress.txt", "w")
system = espressomd.System(box_l=[1.0, 1.0, 1.0])
np.random.seed(seed=42)
p = system.part.add(pos=(0, 0, 0), id=0)
system.time_step = dt
system.thermostat.set_langevin(kT=kT, gamma=gamma, seed=42)
system.cell_system.skin = 0.4
system.integrator.run(1000)
pos_obs = ParticlePositions(ids=(0, ))
vel_obs = ParticleVelocities(ids=(0, ))
c_pos = Correlator(obs1=pos_obs,
tau_lin=16,
tau_max=100.,
delta_N=10,
corr_operation="square_distance_componentwise",
compress1="discard1")
c_vel = Correlator(obs1=vel_obs,
tau_lin=16,
tau_max=20.,
delta_N=1,
corr_operation="scalar_product",
compress1="discard1")
system.auto_update_accumulators.add(c_pos)
system.auto_update_accumulators.add(c_vel)
system.integrator.run(1000000)
c_pos.finalize()
c_vel.finalize()
system.force_cap = 0
# Integration parameters
sampling_interval = 50
sampling_iterations = 200
from espressomd.observables import ParticlePositions
from espressomd.accumulators import Correlator
# Pass the ids of the particles to be tracked to the observable.
part_pos = ParticlePositions(ids=range(n_part))
# Initialize MSD correlator
msd_corr = Correlator(obs1=part_pos,
tau_lin=10,
delta_N=10,
tau_max=sampling_iterations * time_step,
corr_operation="square_distance_componentwise")
# Calculate results automatically during the integration
system.auto_update_accumulators.add(msd_corr)
# Set parameters for the radial distribution function
r_bins = 50
r_min = 0.0
r_max = system.box_l[0] / 2.0
avg_rdf00 = np.zeros((r_bins, ))
avg_rdf11 = np.zeros((r_bins, ))
avg_rdf01 = np.zeros((r_bins, ))
# Take measurements
tau=time_step,
fric=0.01)
system.actors.add(lbf)
system.thermostat.set_lb(kT=4.0e-6)
print("Warming up the system with LB fluid.")
system.integrator.run(5000)
print("LB fluid warming finished.")
# AVB: after this you should have a completely collapsed polymer globule
# AVB: If you want to watch the process of globule formation in Paraview, just change 5000 to 0 in line 100
# configure correlators
com_pos = ComPosition(ids=(0, ))
c = Correlator(obs1=com_pos,
tau_lin=16,
tau_max=loops * step_per_loop,
delta_N=1,
corr_operation="square_distance_componentwise",
compress1="discard1")
system.auto_update_accumulators.add(c)
print("Sampling started.")
for i in range(loops):
system.integrator.run(step_per_loop)
system.analysis.append()
lbf.print_vtk_velocity(outdir + "/fluid%04i.vtk" % i)
system.part.writevtk(outdir + "/vwf_all%04i.vtk" % i)
sys.stdout.write("\rSampling: %05i" % i)
sys.stdout.flush()
c.finalize()
corrdata = c.result()