There is a tutorial at the Opium pseudopotential generation project, see link below. Although you might not want to take the time to fiddle with the software, the tutorial does a good job explaining the different modifications that can be made to norm-conserving pseudopotentials.
http://opium.sourceforge.net/ Scott Beckman Assistant Professor Department of Material Science and Engineering Iowa State University sbeck...@iastate.edu On 7/13/09 2:57 PM, "Hui Tang" <hui.t...@yale.edu> wrote: > When we build a pseudopotential (psp), we froze the inner core states and > treat only the valence electrons due to the fact that the properties of > materials are largely determined by the outer-layer valence electrons. In > order to obtain a psp with good transferability, there should be very small > overlap between core and valence electron distributions which is true for most > light elements. For most the elements, the overlap between core and valence > electron can be so large that the psp built in the usual way cannot lead to > the correct properties of materials composed of that element (e.g., Na, K). > There are two methods to solve the above problem. 1) Nonlinear core > correction, we use an artificial core charge distribution to replace the real > core charge distribution. When building psp, we substract the contribution to > Vxc and VHartree, which comes from the artificial core, and when using the > psp, add the corresponding ones (see PRB 26, 1378). When doing nonlinear core > correction, we don't increase the number of valence electrons but only > increase the cutoff energy for plane-wave calculations due to the added core. > 2) Semicore states, which means including some states that you usually treat > as core states when you build a pseudopotential. For example, when building a > psp for Ca, we not only include 4s, 4p, 3d but also include 3s, 3p in the > valence states. For this method, we include a lot more electrons (e.g. 8 more > e/atom for Ca), and also need a much large cutoff energy because we have > included much more localized 3s, 3p electrons. So including semicore states > will result in much harder calculations. > > In fact, for most cases, nonlinear core correction is already enough for a > good psp and including semicore states is kind of overkill. So my suggestion > is: use the nonlinear core correction when you need it, use semicore states > unless you have to. > > Hui > > > ----- Original Message ----- >> >> From: daijianhong001 <mailto:daijianhong...@163.com> >> >> To: SIESTA-L@listserv.uam.es >> >> Sent: Monday, July 13, 2009 2:42 AM >> >> Subject: [SIESTA-L] semicore state meaning >> >> >> >> >> >> Dear all, >> >> Some pseudopotential includes semicore state.I wonder what is the meaning of >> semicore state and which element includes semicore state? >> >> Best wishes! >> >> Dai >> >> >> >> >> 200万种商品,最低价格,疯狂诱惑你 >> <http://count.mail.163.com/redirect/footer.htm?f=http://gouwu.youdao.com> >
