[Pw_forum] Errors in PS-PK equation

[Lorenzo Paulatto]

On 22/08/17 15:40, 黄志硕 wrote:
> Actually, in the tutorial "Notes on pseudopotential generation" by Paolo 
> Giannozzi, it is said that "Heavy alkali metals (Rb, Cs, maybe also K) 
> have a large polarizable core. PP’s with just one electron may not 
> always give satisfactory results ", so "promoting the highest core 
> states ns and np, or nd, into valence may be a computationally expensive 
> but obliged way to improve poor transferability ". 

Dear Zhishuo Huang,
that guide is not Quotations from Chairman Paolo Giannozzi; 
pseudopotentials for alkali metals do in fact work for a large array of 
applications, you should test it on your system and see how they perform 
(i.e. if you get good lattice parameter, bands, phonons..)

> However, all the PBE 
> PPs of Rb, Cs, even K are with just one electron, and none of them is 
> ionized. This is the first reason I want to generate PP.

There are entire libraries of pseudopotentials outside of the QE website 
where you can find pseudopotentials for Rb, Cs and K witth the semi-core 
states in valence. I think the ones in the GBRV library do 
<https://www.physics.rutgers.edu/gbrv/>, and you probably also have them 
in the pslibrary 
<http://www.quantum-espresso.org/pseudopotentials/pslibrary/>

> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>        Error in routine run_pseudo (1):
>        Errors in PS-KS equation
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Difficult to say with just the error, no input file and no idea what you 
are actually doing except for the fact that the element could be Rb, Cs 
or K. This can happen when the pseudized wavefunctions have strange 
non-physical shape, instead of going smoothly to zero inside the cutoff 
radius, you can plot the all-electrons and pseudo wavefunctions and 
check. Or it could be some gross mistake in the input, like a wrong core 
configurations, or absurd reference energies.


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 442 79822 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/423 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05