Dears
I have a problem during equilibration of system.
I have a simulation box include 2 different crystal. I define 3 groups ( lower,upper,mobile) and I am using the rerax/c potential to simulate the simple tensile test.
as the following commands, I have “flying ice cube” problem in my second step of equilibration. also the lower group separate from mobile group when the “flying ice cube” problem occur.
at first equilibration step I used Langvin thermostat and I didn’t have any problem, but in second step I used berendsen thermostat. I know from Axel advises that this syndrome occurs more when using berendsen thermostat. I used NVT instead but the problem exist yet.
is there any suggestion to avoid this problem corresponding to my commands?
Thanks
Mohammad
boundary p p s
neighbor 3 bin
neigh_modify once no every 2 delay 0 check yes
fix boxrelax all box/relax x 0 y 0
min_style cg
min_modify dmax 0.1 line quadratic
unfix boxrelax
reset_timestep 0
compute new3d mobile temp
compute new2d mobile temp/partial 1 1 0
#-----------#Run-Step 1
velocity mobile create 300 12345 temp new3d mom yes rot yes dist gaussian
fix fixnve all nve
fix fixstep1 mobile langevin 300 300 100 699483
fix_modify fixstep1 temp new3d
fix upperforce upper setforce 0.0 0.0 NULL
fix lowerforce lower setforce 0.0 0.0 NULL
fix loweraveforce lower aveforce NULL NULL 0.0
fix upperaveforce upper aveforce NULL NULL 0.0
thermo 100
thermo_style custom step pe vol temp press lx ly lz
thermo_modify temp new3d
timestep 0.5
run 100000
unfix fixnve
unfix fixstep1
unfix upperforce
unfix lowerforce
unfix loweraveforce
unfix upperaveforce
reset_timestep 0
#-----------#Run-Step 2 #
fix fixnve all nve
fix fixstep2 mobile temp/berendsen 300 300 100
fix_modify fixstep2 temp new3d
fix upperforce upper setforce 0.0 0.0 NULL
fix lowerforce lower setforce 0.0 0.0 NULL
fix loweraveforce lower aveforce NULL NULL 0.0
fix upperaveforce upper aveforce NULL NULL 0.0
thermo 100
thermo_style custom step pe vol temp press lx ly lz
thermo_modify temp new3d
timestep 0.5
run 200000