Shell_model query

Dear lammps user,

I am trying to setup a MD run by using the core/shell parameters. By using the example file and manual of lammps I made an input script for LaMnO3 crystal system to run a NVE simulation with “temp/berendsen” thermostat.

#------------------------INITIALIZATION----------------------------

units metal
dimension 3
boundary p p p
atom_style full

#-----------------------ATOM DEFINITION----------------------------

read_data inp.xyz

group cores type 1 2 3
group shells type 4 5 6

neighbor 2.0 bin
comm_modify vel yes

------------------------FORCE FIELDS------------------------------

kspace_style ewald 1.0e-6
pair_style buck/coul/long/cs 11.0 # A, rho, sigma=0, C, D

pair_coeff * * 0.0 1.0 0.0

pair_coeff 4 6 1545.21 0.3590 0.0 #La-O

pair_coeff 5 6 1267.50 0.3214 0.0 #Sr-O

pair_coeff 6 6 22764.3 0.1490 43.0 #O-O

bond_style harmonic
bond_coeff 1 145.0 0.0
bond_coeff 2 95.0 0.0
bond_coeff 3 42.0 0.0

------------------------ Equilibration Run -------------------------------

reset_timestep 0

thermo 100
thermo_style custom step temp pe etotal press vol cella cellb cellc cellalpha cellbeta cellgamma

compute CSequ all temp/cs cores shells

thermo_modify temp CSequ

velocity bias option

velocity all create 1427 134 dist gaussian mom yes rot no bias yes temp CSequ
velocity all scale 1427 temp CSequ

fix thermoberendsen all temp/berendsen 1427 1427 0.4
fix nve all nve
fix_modify thermoberendsen temp CSequ

2 fmsec timestep

timestep 0.002
run 10000

unfix thermoberendsen

------------------------ Dynamic Run -------------------------------

dump 1 all custom 100 Trajectory_npt_1500 id xu yu zu vx vy vz

run 100000

I want to setup a NPT run for the above.

Can anybody suggest me what modification should I do to the input script.

The initial structure file is attached.

Regard

Omkar

inp.xyz (433 KB)