How to make atoms have temperature but the positions do not change

Dear lammps-users

I want to calculate a wall which is made of Pt atoms. And the wall has temperature but the positions of atoms in the wall can remain unchanged. Here are my commands and the results that the positions of atoms change.

units real

dimension 3

boundary p p p

atom_style full

read_data box.lammps05

mass 1 195.084

mass 2 195.084

pair_style lj/cut 10.2

pair_coeff 1 1 12.064 2.475 10.2

pair_coeff 1 2 12.064 2.475 10.2

pair_coeff 2 2 12.064 2.475 10.2

group downW type 2

group upW type 1

velocity upW create 273.0 881177

fix 6 upW nve

fix 5 upW temp/rescale 100 2000.0 2000.0 0.5 1.0

compute 2 upW temp

thermo 1000

thermo_style custom step temp press c_2

dump 1 all custom 1000 all.lammpstrj id type x y z vx vy vz

run 100000

The results:

The structure at the beginning:

The structure at the end:

Please teach me how I should do to obtain the result I want. Thanks for your help!

EB0B4D73@...6311....jpg

7D4950F8@...6311....jpg

Dear lammps-users

I want to calculate a wall which is made of Pt atoms. And the wall has temperature but the positions of atoms in the wall can remain unchanged. Here are my commands and the results that the positions of atoms change.

to have a temperature, atoms have to move. immobile atoms are at 0K, always.
however, you can limit *how far* they move by using a position
restraint with fix spring/self on those atoms. for details on this
please see the fix spring/self docs.

axel.