Dear Matteo, Thanks for the information, i read the C. Brouder the paper a little bit. I'am still not sure how to choose the polarization vector. For instance, we have a crystal with spacegroup of P42/MNM, point group of 4/mmm. According to the Table in C. Brouder's paper, this is a dichroism compound. Thus, how can we choose the polarization vector when calculating the XAS of this compound? Can you please show me how?
Thanks so much! Cheers, Min Wu 2010-10-12 >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] Xspectra calculation (wumindt2) >Date: Mon, 11 Oct 2010 10:08:16 +0200 > >Dear > > I assume you are talking of the dipolar part only. >For the quadrupolar it is substantially more complicate. >The number of independent calculations that you have >to perform to obtain the isotropic cross section (powder) >depends on the point group of the space group >of your crystal. >It is 1 for a cubic or tetraedric crystal, >2 for a uniaxial crystal and it is 3, 4, 6 for a biaxial >(ot trichroic) crystal. >I suggest you read >C. Brouder J. Phys.: Condens. Matter 2 (1990) 701-738 >for more details. > >M. > > >> >> Message: 3 >> Date: Sat, 09 Oct 2010 22:48:53 +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, >> >> Thanks. >> >> For dichroism compound, do we just need the in-plane and the c-axis >> polarization vectors? >> While for trichroism compound, do we need to calculate three different >> polarization vectors? >> Am i right? >> >> Best regards, >> >_______________________________________________ >Pw_forum mailing list >Pw_forum at pwscf.org >http://www.democritos.it/mailman/listinfo/pw_forum >
