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twoprobe.py
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from calc import *
from units import *
from param import param
import lead as _lead
import conductor as _conductor
param.createdefault("BFIELD_IN_LEADS", True)
class twoprobe:
def __init__(self,conductor,lead_L,lead_R):
self.energy = None
self.bfield = None
self.conductor = conductor
assert type(lead_L) is list
self.lead_L = lead_L
assert type(lead_R) is list
self.lead_R = lead_R
self.Sigma_L = None
self.Sigma_R = None
def set_energy(self,energy):
if self.energy != energy:
self.energy = energy
for l in self.lead_L:
l.set_energy(energy)
for l in self.lead_R:
l.set_energy(energy)
self.conductor.set_energy(energy)
self.Sigma_L = None
self.Sigma_R = None
def set_bfield(self,bfield):
if self.bfield is None or any(bfield != self.bfield):
self.bfield = bfield
self.conductor.set_bfield(bfield)
if 'BFIELD_IN_LEADS' in param:
for l in self.lead_L:
l.set_bfield(bfield)
for l in self.lead_R:
l.set_bfield(bfield)
self.Sigma_L = None
self.Sigma_R = None
def set_disorder(self,disorder,seed=None):
self.conductor.set_disorder(disorder,seed)
def transmission(self,energy=None):
if energy is not None:
self.set_energy(energy)
if self.Sigma_L is None:
self.Sigma_L = []
for l in self.lead_L:
self.Sigma_L.append(l.Sigma_L())
self.Sigma_R = []
for l in self.lead_R:
self.Sigma_R.append(l.Sigma_R())
return self.conductor.transmission_new(self.Sigma_L,self.Sigma_R)
def LDOS(self):
if self.Sigma_L is None:
self.Sigma_L = []
for l in self.lead_L:
self.Sigma_L.append(l.Sigma_L())
self.Sigma_R = []
for l in self.lead_R:
self.Sigma_R.append(l.Sigma_R())
return self.conductor.LDOS(self.Sigma_L,self.Sigma_R)
class twoprobe_nondiagleads:
def __init__(self,conductor,lead_L,lead_R):
self.energy = None
self.bfield = None
self.conductor = conductor
assert isinstance(lead_L,_lead.nondiag_wideband_L)
self.lead_L = lead_L
assert isinstance(lead_R,_lead.nondiag_wideband_R)
self.lead_R = lead_R
self.Sigma_L = None
self.Sigma_R = None
def set_energy(self,energy):
if self.energy != energy:
self.energy = energy
self.lead_L.set_energy(energy)
self.lead_R.set_energy(energy)
self.conductor.set_energy(energy)
self.Sigma_L = None
self.Sigma_R = None
def set_bfield(self,bfield):
if self.bfield is None or bfield != self.bfield:
self.bfield = bfield
self.conductor.set_bfield(bfield)
if 'BFIELD_IN_LEADS' in param:
self.lead_L.set_bfield(bfield)
self.lead_R.set_bfield(bfield)
self.Sigma_L = None
self.Sigma_R = None
def set_disorder(self,disorder,seed=None):
self.conductor.set_disorder(disorder,seed)
def transmission(self,energy=None):
if energy is not None:
self.set_energy(energy)
return self.conductor.transmission_new(
self.lead_L.Sigma_L_diag(),
self.lead_R.Sigma_R_diag(),
self.lead_L.Sigma_L_offdiag(),
self.lead_R.Sigma_R_offdiag(),
)
# data.LEAD_TYPE", "wideband"
# data.LEAD_TYPE", "coating_wideband"
# data.WIDEBAND_ENERGY", 1.0*eV
param.createdefault("LEAD_TYPE", "lopez_sancho")
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,
)