[Pw_forum] problem with Xspectra

[wumindt2]

Dear matteo,

Thank you very much!
I've got the picture now.

BTW, in my previous calculation, i mistakenly extract the core wavefunction
from the pseudopotential WITH a core hole. But the result seems good when compared
with the experiment. Does it happen often?

Cheers,

Min Wu
2010-10-5



>From: matteo calandra <matteo.calandra at impmc.jussieu.fr>
>Reply-To: PWSCF Forum <pw_forum at pwscf.org>
>To: pw_forum at pwscf.org
>Subject: Re:[Pw_forum] problem with Xspectra
>Date: Tue,  5 Oct 2010 10:49:48 +0200
>
>Dear Min Wu,
>
>  the pseudopotentials to be used for the absorbing atom
>in Xspectra are those having
>the label _gipaw, two examples are:
>
>Fe.pbe-sp-mt_gipaw.UPF
>Fe.star1s-pbe-sp-mt_gipaw.UPF
>
>The first one has no core-hole and has full gipaw informations
>while the second one has core-hole and full gipaw informations.
>Gipaw informations mean many things. What you need to know is that
>GIPAW informations include the presence of the
>all-electron wavefunction for the 1s core state.
>
>Now when you run a simulation you first need to calculate the charge
>density in the presence of a core-hole and thus use pseudo
>Fe.star1s-pbe-sp-mt_gipaw.UPF . This is done by a standard pw.x
>scf calculation using this pseudo.
>In a second step you need to calcuate the Xanes cross
>section and this is done by the Xspectra code.
>
>In the calculation of the  matrix element appearing in the
>Xanes cross-section (Fermi golden rule) the initial 1s state
>IN THE ABSENCE of a core hole is needed. This information is contanined
>in the pseudo potential WITHOUT the core hole (Fe.pbe-sp-mt_gipaw.UPF).
>Thus you simply extract this wavefunction using the script given with the
>Xspectra disribution and you put the name of the file produced by the script
>in the input file of the Xspectra program.
>
>You cannot use the 1s core function with the core hole simply because this is
>wrong as the matrix element inthe cross section involves the product
>between the initial and final states and the initial state has no core hole.
>
>M.
>> Message: 1
>> Date: Tue, 05 Oct 2010 00:42:50 +0800
>> From: "wumindt2"

>> Subject: [Pw_forum] problem with Xspectra
>> To: pw_forum at pwscf.org
>> Message-ID:

>> Content-Type: text/plain; charset="gb2312"
>>
>> Hi,
>>
>> I'm a new user of Xspectra.
>>
>> In the Xspectra example given in the pwscf code, it calculates the  
>> XAS using the pseudopotential
>> without core hole level. In this case, we need to extract the core  
>> wavefunction from the GIPAW
>> pseudopotential when we run the xspectra.x.
>>
>> Now there are pseudopotentials with core hole, normally named as  
>> *.star1s*.UPF. So here is
>> my question, after the SCF calculation, do we still need to extract  
>> the core wavefunction from the
>> peusopotential of the absorbing atom?
>>
>> If the answer is yes, then why we choose the core wavefunction from  
>> the pseudopotential as the ground
>> state, rather than the core wavefunction after the SCF calculation?
>>
>> Thanks!
>>
>> Min Wu
>> 2010-10-4
>
>
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