Lost atoms

Dear all

Please tell me what’s wrong with this problem, it is giving lost atom 10976 current 7422,i have tried every thing like, thermo_modify lost ignore tried dt **small to large,changed velocity ,**but got same, lost atom T will be 750 only dont have to change this value.

Please put valuable suggestion,

Thanks in advance

Sample LAMMPS input script for viscosity of Glassy CuZr alloy

variable T equal 750
variable V equal vol
variable dt equal 0.01
variable p equal 2 # correlation length
variable s equal 50 # sample interval
variable d equal $p*$s # dump interval

convert from LAMMPS real units to SI

variable kB equal 1.3806504e-23 # [J/K/ Boltzmann
variable atm2Pa equal 101325.0
variable A2m equal 1.0e-10
variable ps2s equal 1.0e-12
variable convert equal {atm2Pa}*{atm2Pa}{ps2s}*{A2m}{A2m}*{A2m}

setup problem

units metal
echo both
atom_style atomic
dimension 3
boundary p p p
region box block 0 50 0 50 0 50 units box
create_box 2 box
lattice fcc 3.61 orient x 10 0 0 orient y 0 10 0 orient z 0 0 10
region cu block 0 50 0 50 0 50 units box
create_atoms 1 region cu units box
set region cu type/fraction 2 0.5 12393
pair_style eam/fs
pair_coeff * * …/…/…/…/…/potentials/CuZr_mm.eam.fs Cu Zr
run_style verlet
timestep ${dt}
thermo $d
thermo_style custom step temp pe etotal press vol

equilibration and thermalization

velocity all create $T 102486 mom yes rot yes dist gaussian
fix NVT all nvt temp $T $T 10 drag 0.2
run 8000

viscosity calculation, switch to NVE if desired

#unfix NVT
#fix NVE all nve
reset_timestep 0
variable pxy equal pxy
variable pxz equal pxz
variable pyz equal pyz
fix SS all ave/correlate $s $p $d &
v_pxy v_pxz v_pyz type auto file Cu5Zr5.dat ave running

variable scale equal {convert}/({kB}$T)$V*s*{dt}
variable v11 equal trap(f_SS[3]){scale} variable v22 equal trap(f_SS[4])*{scale}
variable v33 equal trap(f_SS[5])

thermo_style custom step temp press v_pxy v_pxz v_pyz v_v11 v_v22 v_v33

run 100000
variable v equal (v_v11+v_v22+v_v33)/3.0
variable ndens equal count(all)/vol
print “average viscosity: $v [Pa.s/ @ T K, {ndens} /A^3”

Anik shrivastava
Senior Research Fellow
Naval Materials Research Lab,DRDO

The usual comments apply. Check that your are being consistent with the units employed. Always make sure that your initial geometry is minimized (and converged). You probably have a bad structure to start with or your units and your potential don’t like each other, etc.