[lammps-users] Why is my atoms not moving in fix thermal/conductivity

Dear All,

I am trying to calculate the thermal conductivity of Li2O. I have the input file as below. The problem is I can’t get a linear temperature profile , even worse the atoms are not viberating at all in VMD. Shall I exchange the KE more frequently or any other mistake I have made?

Thanks in advance for your valuable help

#Li2O simulation

#Initialization

atom_style charge

units metal

dimension 3

newton on on

boundary p p p

#atom definition

lattice custom 2.303 a1 0.0 1.0 1.0 a2 1.0 0.0 1.0 a3 1.0 1.0 0.0 basis 0.0 0.0 0.0 #O lattice

region myregion block 0 5 0 5 0 25 units lattice

create_box 2 myregion

create_atoms 2 box basis 1 2

lattice custom 2.303 a1 0.0 1.0 1.0 a2 1.0 0.0 1.0 a3 1.0 1.0 0.0 basis 0.25 0.25 0.25 basis 0.75 0.75 0.75 #Li lattice

create_atoms 1 box basis 1 1

group Li_ions type 1

group O_ions type 2

mass 1 6.94

mass 2 15.9994

set group Li_ions charge 1

set group O_ions charge -2

#setting

kspace_style ewald 1.0e-6

pair_style buck/coul/long 10

#Alex’s potential

pair_coeff * * 0 0.3010 0

pair_coeff 1 2 828.01 0.2793 0

pair_coeff 2 2 9547.96 0.2192 32

timestep 0.001

velocity all create 293.0 8792 dist gaussian units box

fix flux all thermal/conductivity 1 z 24 swap 1000

compute ke all ke/atom

variable temp atom c_ke[]/0.0001292355

fix 2 all ave/spatial 2 10 100 z 0.0 5 v_temp file tmp.profile units box

thermo_style custom step temp press vol ke f_flux

thermo 100

dump mydump all xyz 10 dumpfile.xyz

run 1000

Dear All,

I am trying to calculate the thermal conductivity of Li2O. I have the input
file as below. The problem is I can’t get a linear temperature profile ,
even worse the atoms are not viberating at all in VMD. Shall I exchange the
KE more frequently or any other mistake I have made?

yes. you are not time integrating any positions.
you need to add a "fix nve"

axel.

Again, LAMMPS will issue a WARNING message (in all caps) about
no time integration fixes defined when the code runs. It is a good idea to pay
attention to those warnings.

Steve