[CPMD-list] Energy conservation etc.

[Axel Kohlmeyer]

On Wed, 2 Nov 2005, Juerg Hutter wrote:

hi,

JH> A side note. If you have enough memory available
JH> you can speed up your calculation using
JH> 
JH>   REAL SPACE WFN KEEP

nope, that doesn't usually have a significant
effect for USPPs - unlike MEMORY BIG, btw.

regards,
      axel.

JH> 
JH> regards
JH> 
JH> Juerg Hutter
JH> 
JH> ----------------------------------------------------------
JH> Juerg Hutter                   Phone : ++41 44 635 4491
JH> Physical Chemistry Institute   FAX   : ++41 44 635 6838
JH> University of Zurich           E-mail: hutter at pci.unizh.ch
JH> Winterthurerstrasse 190
JH> CH-8057 Zurich, Switzerland
JH> ----------------------------------------------------------
JH> 
JH> 
JH> On Tue, 1 Nov 2005 padma at uiuc.edu wrote:
JH> 
JH> > Dear cpmd users,
JH> >
JH> >   I am facing poor energy conservation in CPMD runs of a
JH> > CO2+ water system (one CO2 molecule in 46 H2O) with PBC.
JH> > (The input file used for the MD is given below.)
JH> > The starting configuration was force-field-equilibrated
JH> > structure of the system which is then wavefunction optimized
JH> > to 10.0d-6.
JH> >
JH> > The conservation (slope) of EHAM over a 5 ps run was
JH> > about 10d-4/ps (which, I believe, is atleast one order
JH> > poorer than acceptable value). The kinetic energy of electrons
JH> > and ions looked pretty good with fluctuations about their
JH> > set-values.
JH> >
JH> > Further, hoping that some adjustments in the input parameters
JH> > would improve the situation, a shoter run of about 0.2 ps
JH> > is made (starting from the RESTART file at the end of
JH> > the 5ps run) with the following options:
JH> >
JH> > RESTART LATEST WAVEFUNCTION COORDINATES VELOCITIES NOSEP
JH> >
JH> > QUENCH BO
JH> >
JH> > NOSE IONS
JH> >     300.0  3200.0
JH> > nose electrons
JH> >     0.02  10000.0
JH> >
JH> > (no MASSIVE thermostating for ions and no thermostating
JH> > at all for the electrons)
JH> >
JH> > also in &DFT section the GC-CUTOFF increased
JH> >
JH> >   GC-CUTOFF
JH> >     1.0e-5
JH> >
JH> > But KSH was found greater then EHAM  during the whole run!!
JH> > And the NOSE ENERGY IONS  listed in the AVERAGED QUATITIES at
JH> > the end of the run was negative (~ -0.9 ).
JH> >
JH> > I would be very greatful to know what's going wrong
JH> > and how can I improve the conservation.
JH> >
JH> > best regards,
JH> > Padma
JH> >
JH> >
JH> > &CPMD
JH> >   MOLECULAR DYNAMICS CP
JH> >   optimizE WAVEFUNCTION
JH> >   RESTART LATEST WAVEFUNCTION COORDINATES VELOCITIES NOSEP NOSEE
JH> >   CONVERGENCE
JH> >     1.0e-6  1.0e-6
JH> >   SPLINE POINTS
JH> >     1001
JH> >   TEMPERATURE
JH> >     300.0
JH> >   NOSE IONS MASSIVE
JH> >     300.0  2500.0
JH> >   NOSE ELECTRONS
JH> >     0.02  10000.0
JH> >   MAXSTEP
JH> >     4000
JH> >   TRAJECTORY SAMPLE
JH> >     20
JH> >   TIMESTEP
JH> >     4.0
JH> >   EMASS
JH> >     600.0
JH> > &END
JH> >
JH> > &DFT
JH> >   NEWCODE
JH> >   EXCHANGE CORRELATION TABLE NO
JH> >   FUNCTIONAL BLYP
JH> >   GC-CUTOFF
JH> >     5.0e-6
JH> > &END
JH> >
JH> > &SYSTEM
JH> >   ANGSTROM
JH> >   SYMMETRY
JH> >     1
JH> >   CHARGE
JH> >     0.0
JH> >   CELL
JH> > 11.3 1.0 1.0 0.0 0.0 0.0
JH> >   CUTOFF
JH> >     25.0
JH> > &END
JH> >
JH> >
JH> > &ATOMS
JH> >
JH> > *C_VDB_BLYP.psp NEWF FORMATTED
JH> > LMAX=P
JH> >  1
JH> >
JH> > [COORDINATES ]
JH> >
JH> > *O_VDB_BLYP.psp NEWF FORMATTED
JH> >    LMAX=P
JH> >    48
JH> >
JH> > [ COORDINATES ]
JH> >
JH> > *H_VDB_BLYP.psp NEWF FORMATTED
JH> >    LMAX=S
JH> >    92
JH> >
JH> > [ COORDINATES ]
JH> >
JH> > &END
JH> > _______________________________________________
JH> > CPMD-list mailing list
JH> > CPMD-list at cpmd.org
JH> > http://cpmd.org/mailman/listinfo/cpmd-list
JH> >
JH> _______________________________________________
JH> CPMD-list mailing list
JH> CPMD-list at cpmd.org
JH> http://cpmd.org/mailman/listinfo/cpmd-list
JH> 

-- 
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Axel Kohlmeyer  e-mail: akohlmey at cmm.upenn.edu, web: www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
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