From 6cedb8aaaa2fb04ffcc2c4f0791d512bbce21bd5 Mon Sep 17 00:00:00 2001 From: Alexander Hampel Date: Tue, 5 Nov 2019 11:40:23 -0500 Subject: [PATCH] Extended the documentation for the VASP interface, with more precise statements about the actual implementation. --- doc/guide/conv_vasp.rst | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/doc/guide/conv_vasp.rst b/doc/guide/conv_vasp.rst index fb80eac7..aacccc4c 100644 --- a/doc/guide/conv_vasp.rst +++ b/doc/guide/conv_vasp.rst @@ -24,9 +24,10 @@ Interface with VASP A detailed description of the VASP converter tool PLOVasp can be found in the :ref:`PLOVasp User's Guide `. Here, a quick-start guide is presented. -The VASP interface relies on new options introduced since version -5.4.x. In particular, a new INCAR-option `LOCPROJ` -and new `LORBIT` modes 13 and 14 have been added. +The VASP interface relies on new options introduced since version 5.4.x. In +particular, a new INCAR-option `LOCPROJ +`_) and new `LORBIT` modes +13 and 14 have been added. Option `LOCPROJ` selects a set of localized projectors that will be written to file `LOCPROJ` after a successful VASP run. @@ -35,13 +36,16 @@ labels of the target local states, and projector type: | `LOCPROJ = : : ` -where `` represents a list of site indices separated by spaces, -with the indices corresponding to the site position in the POSCAR file; -`` specifies local states (see below); -`` chooses a particular type of the local basis function. -The recommended projector type is `Pr 2`. The formalism for this type -of projectors is presented in -`M. Schüler et al. 2018 J. Phys.: Condens. Matter 30 475901 `_. +where `` represents a list of site indices separated by spaces, with the +indices corresponding to the site position in the POSCAR file; `` +specifies local states (see below); `` chooses a particular type +of the local basis function. The recommended projector type is `Pr 2`. This will +perform a projection of the Kohn-Sham states onto the VASP PAW projector +functions. The number specified behind `Pr` is selecting a specific PAW channel, see the +`VASP wiki page +`_ for more information. The formalism for this +type of projectors is presented in `M. Schüler et al. 2018 J. Phys.: Condens. +Matter 30 475901 `_. The allowed labels of the local states defined in terms of cubic harmonics are: @@ -55,12 +59,12 @@ harmonics are: * `f`-states: `fy(3x2-y2)`, `fxyz`, `fyz2`, `fz3`, `fxz2`, `fz(x2-y2)`, `fx(x2-3y2)`. -For projector type `Pr 2`, one should also set `LORBIT = 14` in the INCAR file -and provide parameters `EMIN`, `EMAX`, defining, in this case, an -energy range (energy window) corresponding to the valence states. -Note that, as in the case -of a DOS calculation, the position of the valence states depends on the -Fermi level, which can usually be found at the end of the OUTCAR file. +For projector type `Pr`, one should ideally also set `LORBIT = 14` in the INCAR file and +provide parameters `EMIN`, `EMAX`, defining, in this case, an energy range +(energy window) corresponding to the valence states. Note that, as in the case +of a DOS calculation, the position of the valence states depends on the Fermi +level, which can usually be found at the end of the OUTCAR file. Setting `LORBIT=14` will perform an automatic optimization of the PAW projector channel as described in `M. Schüler et al. 2018 J. Phys.: Condens. +Matter 30 475901 `_, by using a linear combination of the PAW channels, to maximize the overlap in the chosen energy window between the projector and the Kohn-Sham state. Therefore, setting `LORBIT=14` will let VASP ignore the channel specified after `Pr`. This optimization is only performed for the projector type `Pr`, not for `Ps` and obviously not for `Hy`. We recommend to specify the PAW channel anyway, in case one forgets to set `LORBIT=14`. For example, in case of SrVO3 one may first want to perform a self-consistent calculation, then set `ICHARGE = 1` and add the following additional @@ -141,4 +145,3 @@ This can be circumvented by setting a bigger value of the threshold in However, do this only after a careful study of the density matrix and the projected DOS in the localized basis. -