Could we modify the exciting Species Files?

exciting
1

Hello exciting community,
I hope everyone is doing well. I have a question regarding the species files. I am simulating LiNbO3, and exciting generates this initial Li and Nb species files:

> <?xml version="1.0" encoding="UTF-8"?>
> <spdb xsi:noNamespaceSchemaLocation="../../xml/species.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
>   <sp chemicalSymbol="Li" name="lithium" z="-3.00000" mass="12652.66897">
>     <muffinTin rmin="0.100000E-04" radius="1.7000" rinf="29.9495" radialmeshPoints="250"/>
>     <atomicState n="1" l="0" kappa="1" occ="2.00000" core="false"/>
>     <atomicState n="2" l="0" kappa="1" occ="1.00000" core="false"/>
>     <basis>
>       <default type="lapw" trialEnergy="0.1500" searchE="false"/>
>       <custom l="0" type="apw+lo" trialEnergy="0.1500" searchE="true"/>
>       <lo l="0">
>         <wf matchingOrder="0" trialEnergy="0.1500" searchE="true"/>
>         <wf matchingOrder="1" trialEnergy="0.1500" searchE="true"/>
>         <wf matchingOrder="0" trialEnergy="-1.8784" searchE="true"/>
>       </lo>
>     </basis>
>   </sp>
> </spdb>
> ~

<?xml version="1.0" encoding="UTF-8"?>
<spdb xsi:noNamespaceSchemaLocation="../../xml/species.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <sp chemicalSymbol="Nb" name="niobium" z="-41.0000" mass="169357.9703">
    <muffinTin rmin="0.100000E-04" radius="2.0000" rinf="27.0044" radialmeshPoints="400"/>
    <atomicState n="1" l="0" kappa="1" occ="2.00000" core="true"/>
    <atomicState n="2" l="0" kappa="1" occ="2.00000" core="true"/>
    <atomicState n="2" l="1" kappa="1" occ="2.00000" core="true"/>
    <atomicState n="2" l="1" kappa="2" occ="4.00000" core="true"/>
    <atomicState n="3" l="0" kappa="1" occ="2.00000" core="true"/>
    <atomicState n="3" l="1" kappa="1" occ="2.00000" core="true"/>
    <atomicState n="3" l="1" kappa="2" occ="4.00000" core="true"/>
    <atomicState n="3" l="2" kappa="2" occ="4.00000" core="true"/>
    <atomicState n="3" l="2" kappa="3" occ="6.00000" core="true"/>
    <atomicState n="4" l="0" kappa="1" occ="2.00000" core="false"/>
    <atomicState n="4" l="1" kappa="1" occ="2.00000" core="false"/>
    <atomicState n="4" l="1" kappa="2" occ="4.00000" core="false"/>
    <atomicState n="4" l="2" kappa="2" occ="3.00000" core="false"/>
    <atomicState n="4" l="2" kappa="3" occ="1.00000" core="false"/>
    <atomicState n="5" l="0" kappa="1" occ="1.00000" core="false"/>
    <basis>
      <default type="lapw" trialEnergy="0.1500" searchE="false"/>
      <custom l="0" type="apw+lo" trialEnergy="0.1500" searchE="true"/>
      <custom l="1" type="apw+lo" trialEnergy="0.1500" searchE="true"/>
      <custom l="2" type="apw+lo" trialEnergy="0.1500" searchE="true"/>
      <lo l="0">
        <wf matchingOrder="0" trialEnergy="0.1500" searchE="true"/>
        <wf matchingOrder="1" trialEnergy="0.1500" searchE="true"/>
        <wf matchingOrder="0" trialEnergy="-2.1446" searchE="true"/>
      </lo>
      <lo l="1">
        <wf matchingOrder="0" trialEnergy="0.1500" searchE="true"/>
        <wf matchingOrder="1" trialEnergy="0.1500" searchE="true"/>
        <wf matchingOrder="0" trialEnergy="-1.3224" searchE="true"/>
      </lo>
    </basis>
  </sp>
</spdb>

How can I include Li core 1s, Nb semicore 4s, and 4p electrons in the self-consistent field calculation? Sorry if my question seems confusing

2

As of my current understanding, exciting is a full-potential all-electron code, so the core and semicore states are explicitly part of the self-consistent cycle. To change how the code treats these states, you can refer to the tutorial here, which even has the example of lithium if you scroll down to the bottom.

3

For example, the Lithium 1s “core” state is included. The core flag just changes how exciting handles the specifics of the muffin tin component of the state, which has implications for calculation precision and speed. Specifically, only high-lying valence states are calculated using the full potential. Deeper core states, which are spatially-localised, are treated in a separate atom-like calculation using only the l=0 component of the MT potential.

You can change the species settings, but you should invest some time into learning the specifics of the basis before doing so.

Cheers,
Alex