[CPMD-list] EHAM always increases in H-containing system

[Axel Kohlmeyer]

On Fri, 19 Oct 2007, liu liuxiandong wrote:

LX> Dear CPMDers,

LX>    I am simulating the water-solid interface using CPMD. When setting all
LX> hydrogen to be D with ISOTOPE keyword, the CP MD runs normally in NVT
LX> ensemble and EHAM keeps constant. Then I set all hydrogen to be H
LX> (setting ISOTOPE mass to be 1.0079), and equilibrate the system with
LX> TEMPCONTROL for 10000 steps. During this run, EHAM keeps contant in the
LX> last 7000 steps. Consequently, I perform the NVT CPMD. Unfortunately, EHAM
LX> always increase even after 10000 steps.
LX> Thanks for any suggestions.

you are not providing enough information to give specific
recommendations. how did you come up with the values for
EMASS (800.0) and TIMESTEP (3.0)? ...and particularly
the NOSE ELECTRONS thermostat?

i would suggest to try again with NOSE ELECTRONS removed.
without seeing any details of system size and so on, it
is hard to guess, but your target value (0.008) looks rather 
small to me, unless you have a very, very small system.

please let us know what kind of analysis you plan do on
your trajectory, since some of your input choices can have
significant side effects...

axel.

LX> 
LX> 
LX> the &CPMD section is as follows,
LX> &CPMD
LX>  MOLECULAR DYNAMICS CP
LX>  RESTART WAVEFUNCTIONS COORDINATES VELOCITIES
LX>  MAXSTEP
LX>  50000
LX> 
LX>  TIMESTEP
LX>  3.0
LX> 
LX>  EMASS
LX>  800.0
LX>  TEMPERATURE
LX>  300.0
LX>  NOSE IONS MASSIVE
LX>  300.0 2760.0
LX>  NOSE ELECTRONS
LX>  0.008 10000.0
LX> &END
LX> 
LX> 
LX> BEST,
LX> 
LX> 
LX> Xiandong Liu
LX> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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