MM_POTENTIAL

Emanuele Coccia emanuele... at gmail.com
Mon Feb 21 11:45:16 CET 2011


Dear CP2K experts,

 I have two very simple questions:

1) What is exactly written in the *-MM_ELPOT_QMMM.qmmmLog file? Is it
the electrostatic potential due to the MM charges? In the case of a
box of 512 water molecules (one of which is a QM deuterated water),
the positive part is localised on the oxygen atoms whereas there's no
"bubble" on the hydrogen atoms. We would expect something like the
POTENTIAL.cube file generated by CPMD, but it's not the case; is the
fact that the file extension is .qmmmLog (and not .cube) somehow
related to this? How could we generate the electrostatic potential
from a QMMM simulation?


&QMMM

  ....

 &PRINT
      &POTENTIAL
      &END
    &END PRINT

...

&END QMMM


2) a general question on molecular dynamics; what about TIMECON for
both the thermostat and the barostat? I can choose the value of
TIMECON for the thermostat looking at the low frequencies of the
system; and for the barostat? It seems that is we use the same value
for both couplings (box water of 512 atoms, NPT classical simulation)
the convergence of the volume assumes a regular profile, if we instead
use a larger TIMECON for the pressure the cell trajectory is
characterized by sharp peaks.

Thank you in advance

Emanuele

Dept. Of Chemistry, University of L'Aquila




More information about the CP2K-user mailing list