Steve,

I am using velocity scaling(fix/temp rescale) as an alternative to thermostat to create a temperature gradient by setting two ends of my structure to two different temperatures. But of those two fixes only one of them is working accurately and the other one is not. The following is the part of my program:

units metal

dimension 3

boundary s s s

atom_style atomic

pair_coeff * * CH.airebo C

#the regions left and right are fixed and temp/rescaling is done to low and high

region 3 block INF 0.1 INF INF INF INF units box

group left region 3

region 4 block 0.1 4.28 INF INF INF INF units box

group low region 4

region 5 block 4.28 97.0 INF INF INF INF units box

group middle region 5

region 6 block 97.0 101.4 INF INF INF INF units box

group high region 6

region 7 block 101.4 INF INF INF INF INF units box

group right region 7

fix 1 left setforce 0.0 0.0 0.0

fix 2 right setforce 0.0 0.0 0.0

velocity all create 300.0 873586443 dist gaussian

velocity left set 0.0 0.0 0.0 units box

velocity right set 0.0 0.0 0.0 units box