[lammps-users] temp/rescale and volume/rescale

Dear all,
I defined a high temperature at the beginning of my simulation in order to speed up the equilibration. I want to slowly decrease the temperature, for that I am using fix temp/rescale within NVE ensemble. However the rescaling of temperature occurs at specified Nstep following a ramped routine rather than coupling with nve. For example behavior of temperature in Kelvin at every Nth step is as follows
400…390…380
but it actually gets different values in between due to NVE.

Same for the fix volume/rescale; when I want to rescale to volume in order to get a more densed system using fix npt since I can not use nve, it scales down the volume irrespect to dynamics.

Do these features consider the interactions between the atoms when applied with a suitable ensemble? In each of the 2 cases I use two fixes that affect the same variable, could this cause problem?

Thanks,
Burcu

Burcu,

There's no problem using fix temp/rescale with fix
nve, but you shouldn't use fix volume/rescale with fix
npt since both fixes affect the volume.

The rescale fixes are "blind" with respect to the
dynamics --- they just rescale the velocities or
volume without considering the dynamics.

For more information on these fixes, see the
documentation for each one:

http://www.cs.sandia.gov/~sjplimp/lammps/doc/fix.html

Paul