[Pw_forum] band symmetry analysis for Pt (example04 in PP directory)

[Miao Gao]

Dear Paolo:
Thank you for your quick response, I have two more questions.
(1) Considering the differences for degree of degeneracy and values of energy bands
between reference and the repeated result, which one should I trust? 
(2) I have calculted the relativistic energy bands of Pt (see attachment), using
the same input parameters as that in example04, except for increasing the K_Point
to 16 16 16 1 1 1 in scf calculation. The calculated relativistic energy bands
of Pt is consistent with PRB 2, 883 (1970). But the symmetry analysis of reference
results is contradictory to PRB 2, 883 (1970)(see the table below). Has bands.x
been tested extensively? Is the symmetry analysis given by bands.x reliable?
-------------------------------------------------------------------------
X point,           energy bands,     reference results, PRB 2, 883 (1970) 
e(  1 -  2) =     10.44178  eV     2   --> G_6+  M_6+ | G_6+
e(  3 -  4) =     10.87347  eV     2   --> G_7+  M_7+ | G_7+
e(  5 -  6) =     17.37445  eV     2   --> G_7+  M_7+ | G_7+
e(  7 -  8) =     17.67776  eV     2   --> G_6+  M_6+ | G_6+
e(  9 - 10) =     18.65959  eV     2   --> G_7+  M_7+ | G_7+
e( 11 - 12) =     19.10266  eV     2   --> G_6-  M_6- | G_6+ Inconsistent
e( 13 - 14) =     26.26903  eV     2   --> G_6+  M_6+ |
e( 15 - 16) =     28.73750  eV     2   --> G_6-  M_6- |
e( 17 - 18) =     30.28069  eV     2   --> G_7-  M_7- |
-------------------------------------------------------------------------
L point,           energy bands,     reference results, PRB 2, 883 (1970)
e(  1 -  2) =     10.17424  eV     2   --> G_4+  L_6+ | L_6+
e(  3 -  4) =     13.14245  eV     2   --> G_5+  L_4+ | L_4+
e(  3 -  4) =     13.14245  eV     2   --> G_6+  L_5+ | L_5+
e(  5 -  6) =     14.15869  eV     2   --> G_4+  L_6+ | L_6+
e(  7 -  8) =     16.90324  eV     2   --> G_4-  L_6- | L_6+ Inconsistent
e(  9 - 10) =     17.29982  eV     2   --> G_4+  L_6+ | L_6- Inconsistent
e( 11 - 12) =     17.96377  eV     2   --> G_5+  L_4+ | L_4+
e( 11 - 12) =     17.96377  eV     2   --> G_6+  L_5+ | L_5+
e( 13 - 14) =     23.35789  eV     2   --> G_4+  L_6+ |
e( 15 - 16) =     33.87781  eV     2   --> G_4-  L_6- |
e( 17 - 18) =     36.95416  eV     2   --> G_4-  L_6- |
-------------------------------------------------------------------------

Best

Miao Gao

---------------------------------------
Ph.D. student of Department of Physics, 
Renmin University of China.
---------------------------------------


> Date: Fri, 12 Apr 2013 19:28:41 +0200
> From: Paolo Giannozzi <paolo.giannozzi at uniud.it>
> Subject: Re: [Pw_forum] band symmetry analysis for Pt (example04 in PP
> 	directory)
> To: PWSCF Forum <pw_forum at pwscf.org>
> Message-ID: <1365787721.3558.8.camel at pania.fastwebnet.it>
> Content-Type: text/plain; charset="UTF-8"
> 
> There is a doubly-degenerate state at 34.84024 eV 
> that is not present in the reference results. It might
> be a consequence of the change of default starting 
> wavefunctions: a small randomization is added to the 
> superposition of atomic wavefunctions. This breaks
> the symmetry and prevents iterative diagonalization
> from "missing" some states (something that in theory
> shouldn't happen, but in practice sometimes does, 
> especially where high symmetry is present)
> 
> P.




-------------- next part --------------
A non-text attachment was scrubbed...
Name: Pt-Bands.png
Type: image/png
Size: 103906 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20130414/aad9702d/attachment.png>