Does anybody know, if I am raising temperature in NAMD with certain frequency, the simulation is held as NVT or NVE? Since, the temperature nor energy is not constant, what type of system it is ?
For example, let's consider such config:
reassignFreq 5
reassignTemp 0
reassignIncr 1
reassignHold 310
In my opinion it's not a continous ensemble of neither NVT nor NVE. In fact, your case is somewhat special:
If you had a thermostat control enabled, like langevin, T would be constant meanwhile, while energy was changing and that stair-wise heating would be a serie of NVT. However, you don't use a real thermostat, but only reassign the temperature without a temperature control, therefore its more a serie of NVE.
Neither NVT nor NVE just a mixture (series) of NVT
I am not awar of any real study of such statistical ensamble,
W Nowak
If you are doing a Simulated Annealing type simulation use a
Isothermal–isobaric ensemble (NPT) with pressure constant. Otherwise your system may get distorted.
It is neither, in fact it is a non-equilibrium system. I suggest that you use MD with a thermostat, preferably the Nose-Hoover Molecular Dynamics. Then, you can change the temperature and wait for several time steps until the system reaches thermal equilibrium. Then change again. In this case you will have a series of NVTs (or even NPT's, there is a special case of Nose-Hoover Hamiltonian for constant pressure as well).
I agree with all that you have not a proper thermodynamic ensemble and most likely your system is out of equilibrium as the energy is not conserver in such experiment and the dynamics of your system is very much artificial if not unphysical. Increasing the temperature in ramps is a protocol that helps you to achieve a new NVT' ensemble at a new temperature (with T'>T) without taking the system very far from equilibrium when you reach T'.
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