[DFTB-Plus-User] Failure in diagonalisation routine with atoms not too close

Mathias Jørgensen mj at inano.au.dk
Wed Jan 20 10:01:34 CET 2016


Hello Ben,

Thank you for the quick reply. The other solvers are much more stable indeed. I find that the RelativelyRobust is about the same performance, as you say, while the Standard seem to be faster for my system.

Thanks!
Mathias


> On 19 Jan 2016, at 13:53, Ben Hourahine <benjamin.hourahine at strath.ac.uk> wrote:
> 
> Hello Mathias,
> 
> implementations of dsygvd are often unreliable. Try the alternative eigensolvers and see if that works:
> 
> Eigensolver = RelativelyRobust{}
> 
> this should be about the same performance but less likely to fail. The qr solver used by standard{} is slower but also should be more reliable.
> 
> Regards
> 
> Ben
> 
> 
> 
> On 19/01/16 12:43, Mathias Jørgensen wrote:
>> Dear DFTB+ community
>> 
>> I have been using the DFTB+ for optimising Mo2C clusters (Mo12C6) without problems. I use it for optimising initial random structures for a genetic algorithm (with atoms positioned randomly within a cell with some minimum interatomic distance). 
>> 
>> Recently I moved to a larger system, MoC24H18, and I very often get the following error:
>> 
>> "Failure in diagonalisation routine dsygvd, non-positive definite overlap! Minor 7688 responsible."
>> 
>> where “7688” differs depending on the initial structure.
>> 
>> For smaller systems the error still occurs but is much less frequent. 
>> I learned from older posts on this error that the problem often has to do with atoms getting too close or other non-physical systems. In my case, however, atoms getting too close it not the problem - I checked a lot of the geometries and ran tests with large initial minimum interatomic distances. Also, I learned that 7688 refers to orbital 7688, but I certainly don’t have 7688 orbitals in my system, Mo(d)C(p)H(s). The error is consistent with respect to initial atomic configuration and it happens at geometry step 0.
>> 
>> What could be wrong?
>> 
>> Best,
>> Mathias
>> 
>> *********
>> Mathias Jørgensen
>> Phd. Stud.
>> Interdisciplinary Nanoscience Center (iNANO), research group of prof. Bjørk Hammer
>> Aarhus University
>> Denmark
>> email: mj at inano.au.dk
>> 
>> _______________________________________________
>> DFTB-Plus-User mailing list
>> DFTB-Plus-User at mailman.zfn.uni-bremen.de
>> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
> 
> -- 
>      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
> 
> 2013/4 THE Awards Entrepreneurial University of the Year
>      2012/13 THE Awards UK University of the Year
> 
>   The University of Strathclyde is a charitable body,
>        registered in Scotland, number SC015263
> 
> 
> _______________________________________________
> DFTB-Plus-User mailing list
> DFTB-Plus-User at mailman.zfn.uni-bremen.de
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user



More information about the DFTB-Plus-User mailing list