[CP2K:4184] augmented basis sets and cholesky issues

[hut... at pci.uzh.ch]

Hi

if you are running a condensed phase system (or just a very
large molecule) augmented basis sets cause problems of
overcompletness. The overlap matrix gets illconditioned and
for example the Cholesky decomposition fails.
What can you do:
- try CHOLESKY OFF in   CP2K_INPUT / FORCE_EVAL / DFT / SCF
  and tune EPS_EIGVAL to a good value for your application
  (same input section)
  This is what is usually done in QC codes
- Augmented basis sets are often not needed in condensed
  systems (the overcompletness is a hint), maybe it is better
  to use triple zeta or higher. Surfaces are tricky as they
  have both types of environments.
- MOLOPT basis sets. They were developed to have diffuse 
  components in the basis and at the same time still have
  a well conditioned overlap matrix (see BASIS_MOLOPT)

regards

Juerg Hutter

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich               E-mail:  hut... at pci.uzh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp2k <cp... at googlegroups.com>
From: Noam Bernstein 
Sent by: cp... at googlegroups.com
Date: 11/13/2012 07:20PM
Subject: [CP2K:4184] augmented basis sets and cholesky issues

Hi - I'm trying to switch from a DZVP basis to the an augmented
version, specifically aug-DZVP-GTH from the GTH_BASIS_SETS
file in the cp2k/tests/QS directory.

1. Is there a better, or more standard, augmented double-zeta basis I could use? 
2. When I do use this basis (instead of DZVP-GTH-BLYP), I get this error

 *****************************************************************************
 *** 12:13:15 ERRORL2 in cp_fm_cholesky:cp_fm_cholesky_decompose processor *** 
 *** 0  err=-300 condition FAILED at line 102                              ***
 *****************************************************************************


 ===== Routine Calling Stack =====  

           11 cp_fm_cholesky_decompose
           10 make_full_all
            9 make_preconditioner
            8 prepare_preconditioner
            7 init_scf_loop 
            6 scf_env_do_scf
            5 qs_energies_scf
            4 qs_forces
            3 velocity_verlet
            2 qs_mol_dyn_low
            1 CP2K 
 CP2K| condition FAILED at line 102
 CP2K| Abnormal program termination, stopped by process number 0

What if anything can I do about this?  The positions come from an
 MM calculation.  Do I have to switch to a different preconditioner?
Is this likely to be an issue with the (well equilibrated) MM initial
positions?

        thanks,
        Noam  
  -- 
 You received this message because you are subscribed to the Google Groups "cp2k" group.
 To post to this group, send email to cp... at googlegroups.com.
 To unsubscribe from this group, send email to cp2k+uns... at googlegroups.com.
  For more options, visit this group at http://groups.google.com/group/cp2k?hl=en.