[lammps-users] error on fix heat

Dear all,

I am trying to use ‘fix heat’ to conduct NEMD simulation, which add and reduce energy from two regions for every n time steps. And I used the new version of fix heat which contains ‘region’ option. While I got this error ’ Could not find fix group ID’. This error came after the fix heat command. The following is the input files.


MD simulation of Ar thermal conductivity


units lj
dimension 3
newton on
boundary p p p
atom_style atomic
neighbor 0.3 bin
neigh_modify check yes
lattice fcc 0.844
region box block -4 4 -4 4 -4 4 units lattice
create_box 1 box
create_atoms 1 box
region up1 block INF INF INF INF -0.5 -0.25 units lattice
region up2 block INF INF INF INF 0.5 0.75 units lattice
region up union 2 up1 up2
region down1 block INF INF INF INF -3.5 -3.25 units lattice
region down2 block INF INF INF INF 3.5 3.75 units lattice
region down union 2 down1 down2
region hot block INF INF INF INF 0.0 0.25 units lattice
group hot region hot
region cold block INF INF INF INF -4.0 -3.75 units lattice
group cold region cold
mass 1 1.0
#mass0 6.633e-26
#epsilon0 1.67e-21
#sigma0 3.405e-10
velocity all create 0.71 458127641 mom yes rot yes dist gaussian units box

Tersoff potential *********************************************************

pair_style lj/cut 2.8
pair_coeff 1 1 1.0 1.0 # LJ parameters for Ar-Ar
fix temp all temp/berendsen 0.71 0.71 0.0466
fix nve all nve
compute ke all ke/atom
variable temp atom c_ke/(1.5*1.0)
fix temp_profile all ave/spatial 1 100000 100000 z lower 0.25 v_temp file temp.profile units lattice
compute up_temp all temp/region up
compute down_temp all temp/region down
variable delta_temp equal c_up_temp-c_down_temp
fix delta_out all ave/time 1 100000 100000 v_delta_temp file delta_temp.dat
thermo_style custom step temp etotal vol
thermo_modify lost warn
thermo 1000


timestep 0.000466
run 100001
unfix temp

fix hot qin heat 1 1.0 region hot
fix cold qout heat 1 -1.0 region cold
variable thermal_conductivity equal^(1.0/3.0)3.405e-102.0f_delta_out*1.67e-21/1.3806504e-23)*6.0/8.0
fix thermal_conductivity_out all ave/time 100000 1 100000 v_thermal_conductivity file thermal_conductivity.dat


run 1000000