[CPMD-list] What are classic energies for CP MD and PI MD?

[Axel Kohlmeyer]

On Wed, 7 Dec 2005, Lan-Feng Yuan (lyuan at Princeton.EDU) wrote:

LY> > 
LY> > axel.
LY> > 

LY>   Well, I certainly use Nose-Hoover chains, otherwise the
LY> temperature cannot be fixed around 150 K (although its fluctuation
LY> is huge because the system is so small). In my understanding, the
LY> instant temperature is simply a constant times the total nuclear
LY> kinetic energy, and the constant has to do degree of freedoms (3N-3
LY> here). The tricky thing is what's ECLASSIC? Just sum of EKS and
LY> nuclear KE? Or thermostat KE also included? If thermostat energy is
LY> also there, then it has not much use in calculating other
LY> properties.

well, here is the beauty of having the source code. you can see
for yourself (and change it if needed). for a regular CP-MD you
have to look into mdmain.F and there you have:

          ECONS=EKINP+ETOT+ENOSE+ENOSP+ECNSTR+EKINCV+VHARM
C
...
          EHAM=ECONS+EKINC


ECONS is ECLASSIC on output. as you can see ECLASSIC is EHAM - EKINC.


axel.

LY> 
LY>   Thanks! Best regards,
LY> 
LY>   Lan-Feng
LY> 

-- 
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Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
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