[Sax-project-users] How to distinguish which is bright and dark exciton with the output of OAS?

[marsamos at democritos.it]

BSE gives you all the energy of the excitons (all excitons), the 
program spectra.x coupled the excitons with linght and give you the 
optical response.

Bright excitons give you a non zero signal in the absorption spectrum, 
Dark ones not.

the optical signal intensity is given by the y-axis in oas.RPAEXC

the optical gap is the energy of the first bright exciton (compare 
y-axis of oas.RPAEXC (use a very small lorentzian broadening in the 
calculation pf the spectrum to have a better energy resolution) with 
the energies found in bse (tag <eigenvalues))

I really recommend to read the tutorial Hedin-lundqvist papers and S. 
Louie papers. It would be easy to understand the meaning of 
input-output.

bests

SaX developers Team

Quoting xiaoyinxie <xiaoyinxie at 126.com>:

> Dear developers:
> Your last reply recommended me to do a optic absorb spectrum 
> calculation to distingush which is the optical gap with spectra.x .
> fanally I obtained a file named oas.RPAEXC . I wondering:
> How to distinguish which is bright and dark exciton with the output of OAS?
> thank you very much !
>    Xie Xiaoyin
>
>
>
> --
>
> ???????,???????!
>
>
> ?2009-05-06,sax-project-users-request at qe-forge.org ??:
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>> Today's Topics:
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>>   1. errors (kazempoor at ph.iut.ac.ir)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Wed, 6 May 2009 13:26:03 +0330 (IRST)
>> From: kazempoor at ph.iut.ac.ir
>> Subject: [Sax-project-users] errors
>> To: sax-project-users at qe-forge.org
>> Message-ID: <15771303.559201241603763627.JavaMail.root at mta.iut.ac.ir>
>> Content-Type: text/plain; charset=utf-8
>>
>>
>>
>> Dear All
>> I want to run example3 for TiO2. I make input file and Then I run in 
>> serial mode execution ,then following error happen:
>> Opening file tio2-gga.export/index.xml
>> Reconstructing the main grid
>> Writing header
>> Writing dimensions
>> Writing cell
>> Writing atoms
>> Writing symmetry operations
>> Writing k-mesh
>> Writing other parameters
>> Writing main grid
>> Writing grids for wfc
>> Writing band structure
>> Writing Eigenvectors
>> Serial execution initialized
>> Time and date: 10:04:21.044   06/05/2009
>> ########################################################################################################################
>> # FROM IOTK LIBRARY, VERSION 1.2.0development
>> # UNRECOVERABLE ERROR (ierr=1)
>> # ERROR IN: iotk_scan_attr (iotk_attr.spp:371)
>> # CVS Revision: 1.19
>> ########################################################################################################################
>> Opening file tio2-gga.export/index.xml
>> Reconstructing the main grid
>> Writing header
>> Writing dimensions
>> Writing cell
>> Writing atoms
>> Writing symmetry operations
>> Writing k-mesh
>> Writing other parameters
>> Writing main grid
>> Writing grids for wfc
>> Writing band structure
>> Writing Eigenvectors
>> Serial execution initialized
>> Time and date: 10:06:54.125   06/05/2009
>> +++
>> efermi   8.09833015707835
>> ########################################################################################################################
>> # FROM IOTK LIBRARY, VERSION 1.2.0development
>> # UNRECOVERABLE ERROR (ierr=1)
>> # ERROR IN: iotk_open_read (iotk_files.spp:487)
>> # CVS Revision: 1.20
>> # unit
>> file=pp_parameters
>> binary=T
>> iostat=29
>> ########################################################################################################################
>> Serial execution initialized
>> Time and date: 10:07:04.763   06/05/2009
>> ########################################################################################################################
>> # FROM IOTK LIBRARY, VERSION 1.2.0development
>> # UNRECOVERABLE ERROR (ierr=1)
>> # ERROR IN: iotk_open_read (iotk_files.spp:487)
>> # CVS Revision: 1.20
>> # unit
>> file=GW_states
>> binary=T
>> iostat=29
>> ########################################################################################################################
>> Serial execution initialized
>> Time and date: 10:07:05.731   06/05/2009
>> ########################################################################################################################
>> # FROM IOTK LIBRARY, VERSION 1.2.0development
>> # UNRECOVERABLE ERROR (ierr=1)
>> # ERROR IN: iotk_open_read (iotk_files.spp:487)
>> # CVS Revision: 1.20
>> # unit
>> file=GW_states
>> binary=T
>> iostat=29
>> ################################################################################################
>>
>> Is anyone tell me what do I do?
>> Thanks a lot
>> Ali Kazempour,Isfahan Uni. Of .Tech, Phys. Dept
>>
>>
>>
>>
>>
>>
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>> End of Sax-project-users Digest, Vol 3, Issue 2
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