[Pw_forum] xspectra calculation

[jiayudai]

Dear Matteo and Min Wu,

Several daysa ago, i said a problem in my calculations with high pressure. With the help of Matteo, the problem has been solved, and that is because of my fault, where i misread the units of ef_r (in Ry here). Thank Matteo.

And i think even for dipolar part, the direction of k vector should be important in some cases, such as the SiO2 in the example. And if we want to compare the results with some experiments, we should cut the contribution of occupied states, that is, cut_occ_states = .true. should be used. But we should shift the position by hand in order to compare the results, cause i think it is very difficult to get the accurate position in DFT, or even in atomic physics, it is a difficult problem to determine the position of spectra. The "ef_r" should be the fermi energy in scf calculation with core-hole, i think.

Am i right?

Jiayu


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Message: 3
Date: Wed, 20 Oct 2010 07:07:16 +0800
From: "wumindt2" 
Subject: Re: [Pw_forum] xspectra calculation
To: pw_forum at pwscf.org
Message-ID: 
Content-Type: text/plain; charset="gb2312"

Dear Matteo,

So when we just do the dipolar part, we don't need to care about the
k vector, right?

Besides, in order to compare with an experimental spectrum, is it necessary to cut
the occupied state below Fermi energy level within our Xspectra calculation ?
In that case, we should set "cut_occ_states" = .true. and 
"ef_r" equal to the fermi energy we got in the scf calculation. Is it?

Best regards,

Min Wu
2010-10

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Jiayu Dai
Department of Physics
National University of Defense Technology, 
Changsha, 410073, P R China
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