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lammps/examples/USER/atc/drift_diffusion/in.no_atoms_ddm
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in.no_atoms_ddm
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# needs description
# DESCRIPTION: haynes-schockley
# continuity eqn: n,t = J,x + (G-R) = D n,xx + mu (n E),x + G - 1/tau (n - n_0)
# w/ J = D n,x + mu n phi,x
# poisson eqn for E-field: epsilon phi,xx = -e (n - p + N_D - N_A)
# w/ E = phi,x
# NOTE: does not conserve electrons even with fixed E field and zero mobility
# if J=0 --> n,x = mu/D n phi,x
echo both
units metal
variable E equal 10.0
variable n0 equal 0.0001
variable dn equal 2.0*${n0}
variable dt equal 0.0000001
timestep ${dt}
atom_style atomic
lattice fcc 1.0
region simRegion block -50 50 0 1 0 1
boundary f p p
create_box 1 simRegion
mass 1 1.0 # need to keep this
atom_modify sort 0 1
# ID group atc PhysicsType ParameterFile
fix AtC all atc drift_diffusion Si_ddm.mat
# ID part keywords nx ny nz region
fix_modify AtC mesh create 100 1 1 simRegion f p p
fix_modify AtC mesh create_nodeset lbc -50.1 -49.9 -INF INF -INF INF
fix_modify AtC mesh create_nodeset rbc 49.9 50.1 -INF INF -INF INF
# fix a temperature
fix_modify AtC initial temperature all 300.0
fix_modify AtC initial electron_temperature all 300.0
fix_modify AtC initial electron_density all gaussian 0 0 0 1 0 0 5.0 ${dn} ${n0}
# isolate system:
# diffusion: dn/dx = 0
# drift : n = 0
fix_modify AtC fix electron_density lbc ${n0}
fix_modify AtC fix electron_density rbc ${n0}
fix_modify AtC fix electric_potential all linear 0 0 0 $E 0 0 1
variable perm equal 0.06
variable nD equal 1.0e-4
fix_modify AtC source electric_potential all ${nD}
variable s equal 10
thermo $s
# f_AtC:1 thermal energy, 2 avg T, 3 electron energy, 4 avg Te, 5 total n
thermo_style custom step cpu f_AtC[1] f_AtC[2] f_AtC[3] f_AtC[4] f_AtC[5]
thermo_modify format 1 %5i format 2 %7.2g
fix_modify AtC output no_atoms_ddmFE $s text
fix_modify AtC extrinsic electron_integration implicit
run 40
# free electric field and allow shielding
fix_modify AtC unfix electric_potential all
fix_modify AtC fix electric_potential lbc linear 0 0 0 $E 0 0 1
fix_modify AtC fix electric_potential rbc linear 0 0 0 $E 0 0 1
fix_modify AtC extrinsic electron_integration implicit 10
run 40
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