the start temperature after minimization


I want to study the effect of temperature on the behavior of a polymer-water system between 273 and 373 K.

The main commands I use are:

minimize 1.0e-06 1.0e-06 100000 100000

fix E1 all nvt temp 0 273 50 tchain 1
thermo 500
timestep 0.5
run 1000000

fix E2 all npt temp 273 273 50 iso 0.1 1 500
thermo 500
timestep 0.5
run 1000000

fix M all npt temp 273 373 50 iso 1 1 500
thermo 500
timestep 0.5
run 2000000

Is minimization conducted at a certain temperature? At Step1, from which temp should we start increasing the temperature (I started from 0K)? At all, for the purpose of equilibration, is it correct to start from low temperatures and then increase it, or from high temperatures and then decrease to the desired temp? High temperatures may be deleterious and break the bonds, so I think 0 K is better.

For Production Run: Step3, is it better that we use npt or nvt?

Thank you very much

Minimization ignores velocities, which are unchanged by
the minimization. A minimization only uses
the current atom coords as a starting point.