[CPMD-list] VDW

[Robert Williams]

Dear Dr. Shemella,

The agreement between 1) the existing very high level ab initio
and experimental results for VDW interactions, and 2) any
BLYP results we obtained with our empirical methods - were
never very pretty.    I suspect that a different damping
function would do better.   We are working on some improvements,
but our focus is still on PBE in part because it has a lower
repulsive potential between 6 and 15 angstroms than most
other functionals.

Best regards,
Bob Williams

Philip Shemella wrote:
> Dear List,
>
> I've been going through 2006 Chem Phys paper* that includes the VDW
> parameters.  My question is regarding the scale factors (using O_TE
> and C_TE as an example):
>
> To go from PBE parameters (shown in Table 2) to BLYP I should divide
> Cab6 = -9.728 by SC = 0.85 and Rab = 4.773 by SR = 0.80 (PBE scale
> factors) and then multiply by the BLYP scale factors of SC = 2.37 and
> SR = 1.06?
>
> Of course I will still test, but I definitely wanted to ask before
> investing too much time.
>
>
> Thanks,
> Phil
>
>
>
>
> * Ref 73: "van der Waals corrections to density functional theory
> calculations: Methane, ethane, ethylene, benzene, formaldehyde,
> ammonia, water, PBE, and CPMD", Robert W Williams and Daksh Malhotraa,
> Chemical Physics, Volume 327, Issue 1, 21 August 2006, Pages 54-62

-- 
Dr. Robert Williams
Department of Biomedical Informatics
Program in Molecular and Cell Biology
Faculty Senate President Elect
Phone: 301-295-3568