# AIMD and velocity scaling in VASP

Typically one does velocity scaling to "heat" their sample with MD.

1. How do we do this in VASP? Is it by setting the SMASS=-1 and MDALGO=0 tags?

2. Why can't we "heat" using a Nose-Hoover thermostat? SMASS=0, MDALGO=2?

*when I tried both methods for "heating" (100 to 600 K) I found the total E increases in method 1 and decreases in method 2. Why is this the case? I'd expect energy to rise since I started in my ground state configuration. I'm using an NVT ensemble by the way (ISIF=2).

Edit: I think my post was too long before so I simplified it

I think I figured out parts of my question. But would really benefit from a VASP/AIMD expert weighing in.

1. This appears to be the correct way of doing velocity scaling in VASP. And you can scale the velocity every NBLOCK steps (but I'm not sure if/when it's more appropriate to scale every 1 step, 10 steps, etc.)

2. Technically you can I think. I set the parameters listed in my question. And also TEBEG = 100 and TEEND = 600. The temperatures and energies rose. I just don't know if this is correct to "heat" this way since I normally see people just do a constant temperature with a Nose-Hoover thermostat and NVT ensemble

*the total E actually decreased in method 2 because the potential energy of the bath decreased. So technically I should just look at E0+EK (the potential + kinetic energy), which does increase as the "temperature increases".