Define interval pressure gcmc

I’m trying to perform a isotherm of methane in range to 0-1 bar.
With fix gcmc I produced a single point to pressure 0.001.
To produce a ramp, how can I made it.
Do I must define one fix for every point or I can define same variable?


fix gcmc does not allow the chemical potential or fugacity (related to pressure) to be ramped. Each invocation of the fix defines a constant value of the fugacity that is imposed during the subsequent MD run. For you application, in which you want to sample a range of pressures, you will have to run a sequence of runs at different fugacities. Each run will equilibrate more quickly if it is started from the last configuration of a previous run at a slightly higher or lower fugacity. The easiest way to accomplish this is by looping over a list of desired fugacities. Here is an example of that for a thermostat:

variable temp index 3.0 4.0 5.0
label temp_loop
fix tstat all langevin {temp} {temp} 0.1 12345

run 100

next temp
jump SELF temp_loop