[Pw_forum] Some questions about IFC from PWSCF
john Bob
bobjohn.lzu at gmail.com
Mon Oct 11 11:22:18 CEST 2010
Dear Stefano:
Thank you very much for the answers. I lernt much from those. In some
textbook the force constant matrix are
( L L' )
F ( )
alpha,beta ( K K' ) L is the index of cells, K index of
different atoms.
(1) Can I rewrite the F_(alpha,beta)^(na,nb)(R) as
( 0 L' )
F ( ) while L' is L(a,b,c)
L(R) ?
alpha,beta ( na nb )
(2) F_{alpha,beta} matrix is 3X3 matrix. And It acts like other two rank
tensor ( dielectric tensor, electric conductivity tensor) under symmetry
operations ? The independent parameters can be decided by group theory ?
one for cubic system.
(3) I pick up the
" x x 1 1
2 1 1 x.xxxx "
lines
================
1 1 1 1
1 1 1 4.30811843056E-02
2 1 1 1.49655475926E-02
1 2 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
1 3 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
2 1 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
2 2 1 1
1 1 1 4.30811843056E-02
2 1 1 2.68996333333E-03
2 3 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
3 1 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
3 2 1 1
1 1 1 0.00000000000E+00
2 1 1 0.00000000000E+00
3 3 1 1
1 1 1 4.30811843056E-02
2 1 1 2.68996333333E-03
==========================
why Fxx /= Fyy = Fzz ?
I am sorry for my poor english. Also sorry for so many annoying question,
self-teaching is a hard and careful work.
Dr Zhou Bo
Norhwest University Xi'an China
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