[DFTB-Plus-User] Max Number of Atoms

Benjamin Hourahine benjamin.hourahine at strath.ac.uk
Tue Oct 7 00:26:16 CEST 2008

Hello Marcelo,

I'll need some more information to give an accurate answer, but
if I assume all of the atoms have an SP basis, you have SCC 
turned on, are using molecular boundary conditions (not periodic),
no spin polarization, and the 'standard' or 'relatively robust' 
choice of eigensolvers then I'd estimate your memory requirements
at about 17 Gb for that system.

If you use the default eigensolver (divide and conqer) this would rise
to a peak of about 28 Gb when it requires workspace. Similarly, changing
any of the above calculational conditions could also modify the memory use.

This suggests you are running out of memory. What exactly is the 
'unexpected error'?



    Dr. B. Hourahine, Department of Physics, SUPA, University of Strathclyde,
      John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, United Kingdom
    Ph +44 141 548 2325 FAX +44 141 552 2891 benjamin.hourahine at strath.ac.uk

The University of Strathclyde is a Scottish registered charitable body, number SC015263

-----Original Message-----
From: dftb-plus-user-bounces at dftb-plus.info on behalf of Marcelo Zimmer
Sent: Mon 06/10/2008 19:47
To: User list for DFTB+ related questions
Subject: [DFTB-Plus-User] Max Number of Atoms
Hello all DFTB+ users,

I`d like to know what is the maximum number of atoms that DFTB+ can carry on
calculation for a molecule. I`m trying to compute approx. 8,000 atoms and
I`m having unexpected error during the first SCC cycle. I`m trying to run
this job under 8 Intel(R) Xeon(R) CPU E5420 @ 2.50GHz with 16Gb of RAM.

Thank you in advance,

Marcelo Zimmer

                               Marcelo Zimmer S. Flores
                                 (PhD Physics Student)

       Universidade Estadual de Campinas - UNICAMP
       Instituto de Fisica Gleb Wataghin - IFGW
       Grupo de Solidos Organicos e Novos Materiais - GSONM
       Departamento de Fisica Aplicada (DFA) - Room 61
       Campinas - Sao Paulo - Brazil
       Caixa Postal: 6165
       zimmer at ifi.unicamp.br

More information about the DFTB-Plus-User mailing list