[DFTB-Plus-User] eigenvec.out

Benjamin Hourahine benjamin.hourahine at strath.ac.uk
Sat Oct 12 16:51:37 CEST 2013

Dear Mani,

you have an arbitrary global phase of pi, this is harmless for the properties of the system
(eigenvectors are defined up to a global phase). 
As to why its happening this could either be due to working with the transpose of the 
matrices (most likely) or a slightly different eigensolver.



      Dr. B. Hourahine, SUPA, Department of Physics,
    University of Strathclyde, John Anderson Building,
            107 Rottenrow, Glasgow G4 0NG, UK.
    +44 141 548 2325, benjamin.hourahine at strath.ac.uk

  Strathclyde 2012 THE Awards UK University of the Year

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From: dftb-plus-user-bounces at dftb-plus.info [dftb-plus-user-bounces at dftb-plus.info] on behalf of Mani Farjam [farjam at nano.ipm.ac.ir]
Sent: 12 October 2013 12:25
To: User list for DFTB+ related questions
Subject: [DFTB-Plus-User] eigenvec.out

Dear All,

I am working on an application which involves graphene, a periodic system
for the purpose of the present question. I need the eigenvectors and the
overlap matrix for my application, which are conveniently provided by the
dftb+ code in eigenvec.out, eigenvec.bin and overreal.dat. Now my question
is why are the eigenvector coefficients in these files seem to be complex
conjugated. To check, I did the eigenvalue problem
                             H C = E S C
using H and S given in hamsqr1.dat and oversqr.dat, and the eigenvectors indeed
came out as complex conjugates of those in eigenvec.out file.

Thank you in advance for your comments.

Best regards,

Mani Farjam

Dr. Mani Farjam
School of Nano-Science, Institute for Research in Fundamental Sciences
Tehran, Iran

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