def create_from_chain(chain,conductor_size,contact_size_L=1,contact_size_R=1):
conductor = _conductor.create_from_chain(chain,conductor_size)
if param.LEAD_TYPE == 'wideband':
lead = _lead.wideband(
contact = where(chain.H_hop,1.0,0.0)*eV,
factor=param.WIDEBAND_ENERGY/eV**2,
)
elif param.LEAD_TYPE == 'coating_wideband':
if 'COATING_WIDEBAND_N_CONTACT' in param:
contact = matrix(zeros((chain.N_atoms,)*2,'D'))
for n in range(param.COATING_WIDEBAND_N_CONTACT):
contact[n,n] = 1.0*eV
else:
contact = matrix(eye(chain.N_atoms))*1.0*eV
lead = _lead.wideband(
contact = contact,
factor=param.WIDEBAND_ENERGY/eV**2,
)
elif param.LEAD_TYPE == 'lopez_sancho':
tunneling = 1
if "TUNNELING_FACTOR" in param:
tunneling *= param.TUNNELING_FACTOR
lead = _lead.lopez_sancho(
chain,
tunneling = tunneling,
)
return twoprobe(
conductor,
[lead]*contact_size_L,
[lead]*contact_size_R,
)
def create_from_aperiodic(aperiodic,contact_length_L,contact_length_R):
conductor = _conductor.create_from_aperiodic_triozon(aperiodic)
diameter = max([norm(a.pos[:2]) for a in aperiodic.cells[0].atoms])
mindiam = diameter - param.GRAPHENE_CC_DISTANCE*0.5
lead_L = []
lead_R = []
finished = False
for n in range(len(aperiodic.cells)):
atoms = aperiodic.cells[n].atoms
contact = matrix(zeros((len(atoms),)*2,'D'))
j = 0
for i in range(len(atoms)):
if atoms[i].pos[2] > contact_length_L:
finished = True
else:
if norm(atoms[i].pos[:2]) >= mindiam:
contact[j,i] = 1.0*eV
j += 1
lead_L.append(_lead.wideband(
contact[:j,:],
factor=param.WIDEBAND_ENERGY/eV**2,
))
if finished:
break
for n in reversed(range(len(aperiodic.cells))):
atoms = aperiodic.cells[n].atoms
contact = matrix(zeros((len(atoms),)*2,'D'))
j = 0
for i in range(len(atoms)):
if atoms[i].pos[2] < aperiodic.length - contact_length_R:
finished = True
else:
if norm(atoms[i].pos[:2]) >= mindiam:
contact[i,j] = 1.0*eV
j += 1
lead_R.append(_lead.wideband(
contact[:,:j],
factor=param.WIDEBAND_ENERGY/eV**2
))
if finished:
break
lead_R.reverse()
return twoprobe(
conductor,
lead_L,
lead_R,
)