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lammps/examples/USER/atc/fluids/in.poisson
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in.poisson
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# test poisson solver
# * seems to have error in fix_flux
echo both
units metal
variable E equal 20.0
variable nx equal 32
# allow charges
atom_style full
dielectric 1.
dimension 3
boundary f p p
lattice fcc 4.08 origin 0.25 0.25 0.25
region BOX block 0 16 0 3 0 3
create_box 1 BOX
create_atoms 1 region BOX
pair_style lj/cut 13.
pair_coeff * * 0.2381 3.405
mass * 39.948
group real region BOX
set group real charge 1
###########################################################################
#fix EFIELD all efield $E 0.0 0.0
###########################################################################
fix ATC real atc species_electrostatic Ar_species.mat
fix_modify ATC add_species ion type 1 ### <<<<<
#fix_modify ATC add_species REAL group real
fix_modify ATC include atomic_charge
fix_modify ATC internal_quadrature off
fix_modify ATC extrinsic short_range off
fix_modify ATC mesh create ${nx} 1 1 BOX f p p
fix_modify ATC atom_element_map eulerian 1
fix_modify ATC atom_weight multiscale
fix_modify ATC initial mass_density all 0.
#fix_modify ATC initial charge_density all 0.
###########################################################################
variable n equal count(real)
print "number of atoms: $n"
timestep 0.0
thermo 1
compute Fx real reduce sum fx
compute Fy real reduce sum fy
thermo_style custom step etotal temp press pe c_Fx c_Fy
fix_modify ATC output poissonFE 1 text binary
# (1) all fixed
fix_modify ATC fix electric_potential all linear 0 0 0 $E 0 0 0 0
run 1
# (2) Dirichlet
# NOTE with correct density solution is very close
#fix_modify ATC fix charge_density all 0.0588951459091903
fix_modify ATC unfix electric_potential all
fix_modify ATC mesh create_nodeset lbc 0.0 0.0 -INF INF -INF INF
fix_modify ATC mesh create_faceset lbc 0.0 INF -INF INF -INF INF
fix_modify ATC mesh create_faceset rbc -INF 16.0 -INF INF -INF INF
fix_modify ATC fix electric_potential lbc 100.0
run 1
# (3) Neumann
fix_modify ATC fix_flux electric_potential rbc 0.5
run 1
# (4) Robin eps_1 phi'_1 = eps_2/L_2 (phi_{L_2} - phi)
fix_modify ATC unfix_flux electric_potential rbc
fix_modify ATC fix_robin electric_potential rbc 0.5 -0.00001
run 1
# (5) Robins on the left and Robins on the right
fix_modify ATC unfix electric_potential lbc
fix_modify ATC fix_robin electric_potential rbc 0.01 -0.0001
fix_modify ATC fix_robin electric_potential lbc 0.01 -0.0001
run 1
#fix_modify ATC fix charge_density all 0.0
#run 1
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