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[zhangtingPKU <zhangting@pku.edu.cn>]

Matthieu Verstraete,您好！

        Thanks! Your suggestion is quite useful

======= 2006-05-22 10:33:00 您在来信中写道：=======

>>    In PRB 53,R7575, the scatting matrix element of e-ph Hamiltonian 
>> seems have no relation to the phonon amplitude?  In the article, 
>> equation (1), the Hamiltonian in the middle is just the phonon 
>> polarization vector times the gradient of the self-consistent potential. 
>> This is quite different compared with the equations in Mahan's "Many 
>> particle Physics".
>the perturbed hamiltonian should be dotted into the phonon displacement 
>vector. The difference with the polarization vector is the 1/sqrt(M) which 
>is present in eq (1). In Amy we trust!
>
>> Another question: Also in the PRB article,equation (2), there are two 
>> delta function delta(Enk-Ef)*delta(En'k'-Ef). Does this mean before and 
>> after scattering with phonon,the electron states should both have the 
>> same energy,which equals to Ef?
>yes.
>
>> This is strange. I'm interesting in the 
>> scatting of phonons and non-equilibrium "hot" electrons, If the ABINIT 
>> code could only handle the e-ph coupling just at the fermi level, it 
>> will be a great depression to me.
>Well... valium? Or check the publications by Mauri and Ferrari on hot 
>phonons. PWSCF may be able to do something. Or you can code in abinit. It 
>shouldn't be a huge change, but I haven't looked at it in detail. For the 
>moment the FS is taken into account with either the tetrahedron method or 
>a smearing width. With the latter you can increase the temperature and get 
>a wider contribution to the FS. That's a start, but there should also be 
>something about the finite T of the phonons themselves somewhere. Dunno.
>
>>    The third question: dose the GKK file contain the scattering matrix 
>> elements? I can't understand its format.Can someone tell me how the bulk 
>> S-matrix data organised in the GKK file? Can I find a detailed 
>> explaination of the format,and the meaning of date in such *.ep_* files?
>The gkk file contains the raw perturbations generated by abinit from 
>phonon runs: perturbation of 1 atom in 1 reduced direction for 1 qpoint, 
>for all atoms and directions but for the irreducible qpoints only. If you 
>look at the input for mrggkk you can set the output to ascii text if you 
>really want to look at them (huge file though). In the latest version 
>(released in a few days) you'll have access to flags which let you write 
>the actual gkk matrix used in the code to disk instead of keeping 
>everything in memory. However these matrices contain an intermediate 
>quantity used for interpolation
>
>gamma=<psi_k+q | H_q,a,idir | psi_k > <psi_k | H_q,b,jdir | psi_k+q>
>
>or the same thing dotted with the displacement vectors then rotated to the 
>cartesian reference frame (q dropped, sum over everything):
>
>e^j_a',idir' d^j_a,idir gamma d^j_b,jdir e^j_b',jdir'
>
>Anyhow, this may not answer your question, but if you want the standard 
>g_kk' matrices out you will have to write a few lines of code in 
>src/07ddb/completeperts.F90 and src/07ddb/nmsq_gam_sumfs.F90
>
>Matthieu
>
>-- 
>================================================================
>Dr. Matthieu Verstraete                 mailto:mjv500@york.ac.uk
>Dept. of Physics, University of York,     tel: +44 1904 43 22 08
>Heslington, YO10 5DD York, United Kingdom fax: +44 1904 43 22 14

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　　　　　　　　zhangtingPKU
　　　　　　　　zhangting@pku.edu.cn
　　　　　　　　　　2006-05-23