[Pw_forum] Shall we calculate some of the parameters by USPP and some other properties by norm conserving PP for same compound?

[Sudha Priyanka]

Dear Eduardo,
    Thank you very much for your clear explanation and thanks for the link.


With warm regards
Sudha Priyanka G
Assistant Professor,
Lady Doak College,
Madurai, Tamilnadu, India.

On Sun, Jan 14, 2018 at 9:23 AM, Eduardo Menendez <eariel99 at gmail.com>
wrote:

> Dear Sudha,
> One expects that all the pseudopotentials lead to the same electronic
> structure that an all-electron calculation. Small numerical differences are
> expected.
> This page is useful https://molmod.ugent.be/deltacodesdft for better
> understanding
> You should test that the density of states or the bands, are "the same"
> computed with both sets of peudopotentials. There will be small numerical
> differences. You should also check the lattice parameteres. Variations
> smaller than 1% (using the same xc functional) are reasonable. To compute
> optical properties with the NC you may use the relaxed structure obtained
> either with USPP or with NC. Small numerical differences are also expected
> and are acceptable. Care is needed if the differences become  qualitative.
> If you use the USPP structure, with NC the same strusctire is stressed, and
> the stress and  cause splitting of some levels and some peaks in the
> optical properties.
> Best regards
> Eduardo
>
> --------- Mensaje reenviado ----------
> From: Sudha Priyanka <sudhapriyanga24 at gmail.com>
> To: PWSCF Forum <pw_forum at pwscf.org>
> Cc:
> Bcc:
> Date: Fri, 12 Jan 2018 04:25:20 -0800
> Subject: [Pw_forum] Shall we calculate some of the parameters by USPP and
> some other properties by norm conserving PP for same compound?
> Dear Experts,
>    I did scf and other calculation by using USPP, but in epsilon
> calculation (optical properties) I have no option but have to use only norm
> conserving PP, Is this correct? Will it make any difference? Shall I
> compare the calculated properties and parameters by using these different
> pseudopotentials? For example, If I have calculated electronic properties
> by USPP and optical properties by norm conserving PP, can I do
> interpretation of these properties for the same compound?
>
> With warm regards
> Sudha Priyanka G
> Assistant Professor,
> Lady Doak College,
> Madurai, Tamilnadu, India.
>
>
>
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