[QE-users] Missing d orbital in projected band structure of CaC6

[Giovanni Cantele]

Dear Bruce,

if I'm not wrong you're using this pseudopotential:
http://pseudopotentials.quantum-espresso.org/upf_files/Ca.pbe-spn-rrkjus_psl.1.0.0.UPF

If you look inside you see that it has been generate with this valence
configuration:
    nl pn  l   occ       Rcut    Rcut US       E pseu
    3S  1  0  2.00      1.200      1.300    -3.461142
    4S  2  0  2.00      1.200      1.300    -0.276804
    3P  2  1  6.00      1.400      1.600    -2.058527
    4P  3  1  0.00      1.400      1.600    -0.103085

As such, when you try to project a band structure of a system containing
this atom, it will only be able to project on 3S, 4S, 3P and 4P states.
You may also check this by looking, inside the UPF file, for the string
PP_GIPAW_ORBITAL
After lines such that
<PP_GIPAW_ORBITAL.1 index="1" label="3S" l="0"
cutoff_radius="0.000000000000e0" ultrasoft_cutoff_radius="0.000000000000e0">
you find the radial part of the corresponding atomic wfc to be used for the
projection. Therefore, if an orbital is not included, the code does not
have access to the radial part of the wfc and will not be able to make any
projection.

Giovanni

-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it <giovanni.cantele at spin.cnr.it>
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home


Il giorno mar 25 lug 2023 alle ore 09:40 Bruce Wang <p15.wang at hdr.qut.edu.au>
ha scritto:

> Dear QE users and developers,
>
> I am currently working on calculating the projected band structure of CaC6
> using quantum espresso with GGA+UItrasoft pseudopotential (
> Ca.pbe-spn-rrkjus_psl.1.0.0.UPF). However, I have encountered an issue
> with obtaining the 3d orbital wavefunctions for Calcium.
>
> I followed the QE PP examples, and I have managed to obtain the 4s and 3p
> orbitals. The 3d orbital was missing while it should existed.
>
> I would greatly appreciate any guidance on how to retrieve the 3d orbital
> character of Calcium for my projected band structure calculations.
>
> Thank you for your time and assistance.
>
>
> Regards,
> Bruce
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