[CPMD-list] B3LYP with CPMD?

[Axel Kohlmeyer]

Lan-Feng Yuan wrote:
>   Dear CPMD people,
> 
>   I heard that hybrid functionals like B3LYP are terribly slow in CPMD. While the
> paper "molecular dynamics simulation of liquid water: hybrid density functionals"
> (JPCB, 2006, 110, 3685) adopted a bunch of methods to make B3LYP water simulation
> possible, which is very interesting. As they show, hybrid is now only 40 times
> slower than pure DFT. Are these methods incorporated in current version 3.11? What

yes. hartree-fock exchange with distance screening is available in 3.11.
please see the version history in the manual:

- Distance screening for HFX calculation and hybrid funcional for PBC


> do you think about the perspective of using hybrid based on plane wave?

this is very much a matter of taste and of how much CPU time you are
willing to spend on this method. the improvement is undeniable, however
for most practical applications, you have to compare these improvements
to other sources of errors, e.g. finite size effects, insufficient statistics, 
the CP-method itself (when running CP-dynamics, that is). personally, i'd
rather use the hybrid functional results as an estimate of the error for
the 'pure DFT' results and invest the additional CPU time to get better
statistics or larger systems or use a better converged (=larger) basis set
(note that the authors of the paper point out the 70ry cutoff is at the
lower end of being converged and that results change with larger basis sets)
or a combination of it.

cheers,
      axel.

> 
>   Thank you very much! Best regards,
> 
>   Lan-Feng
> 
> 
> 
> 
> ------------------------------
> -------------------------------------------------
> Dr. Lan-Feng Yuan,
> Associate Professor,
> Hefei National Laboratory for Physical Sciences at the Microscale,
> University of Science and Technology of China,
> Hefei, Anhui 230026, People's Republic of China
> Email: yuanlf at ustc.edu.cn
> Telephone: 86-551-3600994
> -------------------------------------------------
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-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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