Thanks for both your answers. On Fri, Oct 23, 2009 at 6:23 PM, Javier Junquera <[email protected]>wrote:
> > Dear Nicolas: > > As you say, for a meaningful comparison > you should keep everything constant > (geometry, mesh cutoff, number of k-points, > pseudopotentials, etc.) during your variational > minimization of the energy or enthalpy > as a function of the basis set parameters. > > Usually, what I have done is to choose a sensible > reference geometry with respect the problem > you are dealing with. > > If the size of the basis is large enough, > then it would have flexibility to adapt to different > environments, and the transferability > (property of the basis to keep their performance > when transferred to different systems than the ones > they were optimized for) should be sufficiently good. > Hope this helps, > > Javier > > > > Hello, >> >> I'm trying to use the simplex algorithm to optimize a basis for my systems >> elements. I'm wondering whether I should do this on a fixed geometrical >> structure for every tested node of the basis set or let the system relax for >> each basis set tested. To do a meaningful comparison between two basises, I >> would argue for the former case. However, the latter may be better as the >> total energy of the system (which is minimized by the simplex algorithm) may >> vary strongly if the system is not relaxed. >> >> Any thoughts on this? >> >> Thanks in advance, >> Nicolas Leconte >> > > > -- > ------------------------------------------------------------------------- > Javier Junquera > > Ciencias de la Tierra y Fisica de la Materia Condensada (CITIMAC) > Avenida de Los Castros s/n > Facultad de Ciencias > Universidad de Cantabria > E-39005 Santander, Cantabria > Spain > > web-page: http://personales.unican.es/junqueraj > e-mail: [email protected] > Tel: (+34) 942 20 15 16 > Fax: (+34) 942 20 14 02 > > >
