Dear S. Appalakondaiah,
As a matter of fact the cells are not very different: If you exchange
the two vectors and take the inverse of the third one you will get the
other case. Figuring out the corresponding directions is a rewarding and
useful exercise - you might also learn something about the symmetry
operations, three-dimensional lattices etc while doing it. Good Luck! :)
Greetings from Paris,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Tue, 16 Dec 2014, Kondaiah Samudrala wrote:
Dear Sir,
I Completed the Phonon calculations with IBRAV=7 option...Its quite difficult
to reperform the calculations. Can you please provide the IBZ path or source
for obtain the IBZ???
with regards
S. Appalakondaiah
PhD student
University of Hyderabad
On Tue, Dec 16, 2014 at 1:22 AM, Kondaiah Samudrala <[email protected]>
wrote:
Dear all,
I am still confused with notation of Ibrav=7 in pwscf. The IBRV=7 primitive
cell vectors in pwscf are quite different from any other. See below for two
cases of primitive vectors IBRAV=7
Case1
For. e.g. In pwscf primitive vectors of IBRV=7 are
crystal axes: (cart. coord. in units of a)
a(1) = ( 0.500000 -0.500000 c/a)
a(2) = ( 0.500000 0.500000 c/a )
a(3) = ( -0.500000 -0.500000 c/a )
Case 2
On the other hand, generally people used as (from published papers)
crystal axes: (cart. coord. in units of a)
a(1) = ( -0.500000 0.500000 c/a)
a(2) = ( 0.500000 -0.500000 c/a )
a(3) = ( 0.500000 0.500000 -c/a ) .
This variation leads to changes in reciprocal vectors and then IBZ path. >From
Wikipedia (http://www.sciencedirect.com/science/article/pii/S0927025610002697) and
http://www.cryst.ehu.es/ , I obtained the IBZ path for
case 2. But, what about the IBZ path of case 1 primitive cell vectors?? Is
both are same ??? But Xcrysden showing something else than regular Gamma, Z,
Sigma, P and N points .
I feel puzzled, would some one give some idea about this? any help will be
appreciated
with regards
S. Appalakondaiah
PhD StudentUniversity of Hyderabad
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