[Pw_forum] constraints in the ionic dynamics
Axel Kohlmeyer
akohlmey at cmm.chem.upenn.edu
Wed Nov 14 06:19:17 CET 2007
On Tue, 13 Nov 2007, alan chen wrote:
AC> Dear PWSCF users,
dear hanghui,
AC> I am now trying to impose some constraints in the ionic dynamics.
AC> However, after I checked the code I found that if I use 'bfgs' algorithm for
AC> 'relax' calculation, the constraints are not implemented in the code. It
implementing constraints in a geometry optimization (unlike in
an MD) is a non-trivial task. many codes i know "fake" them by
using a very, very stiff force constant. using damped dynamics
is a reasonable alternative to BFGS and will allow constraints.
ceers,
axel.
AC> seems that contraints can only be imposed in the molecule dynamics using
AC> Verlet algorithm. Is that true? Any one can share his or her experience in
AC> imposing contraints in the ionic dynamics?
AC> Thank you very much.
AC>
AC> Hanghui
AC> Department of Physics
AC> Yale University
AC>
--
=======================================================================
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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If you make something idiot-proof, the universe creates a better idiot.
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