DFT-D in Nwchem

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Hello,
It is impossible to change some of the dispersion correction coefficients in DFT-D method. For example the C6 atomic coefficients and radii scaling factor are fixed. When one needs to change the DFT-D method for some type of interactions it is crucial to change some of the coefficients.

I changed my version of nwchem to include c6 and radii scaling read from input file but I don't know the internal structure of nwchem good enough to do it properly. I've made only ad hoc corrections. I someone wants it I could include my files.

I noticed some things in code:
-In seems that damping function coefficient alpha is stored as dft:alpha in dft_input.F file, but xc_vdw.F tries to read dft:vdwalpha entry from database.
-Alpha is set to 20.0 (because database read fails). The default value of alpha should depend on ivdw: it was 23.0 in original Grimmes paper (so 23.0 if ivdw=1 and 20.0 otherwise).
- In xc_vdw.F line 392: c6 values are unnecessary set to be -1.

Best regards,
Karol Struty?ski

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Hi Karol,

Can you send me your changes so that I can take a look ?

Best regards,
Niri



Niri Govind, Ph.D.
NWChem Development
Pacific Northwest National Laboratory

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Hi Karol,

My email address is: niri.govind@pnl.gov

Best regards,
-Niri

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Hello,
I'd like to upload the file with the changes, but I have no idea how. So I send it to you by mail.

As I mentioned they are rather crude. Especially the part that introduce user defined c6 coefficients. I set it to print some more information in medium print level.

You may unpack the file in your NWCHEM_TOP directory and the files will pop to the right places. All old files are stored as file-org. When recompiling you may have to remove the $NWCHEM_TOP/lib/LINUX64/libnwdft.a file.

Best Regards,
Karol Strutynski
Edited On 8:03:46 AM PST - Mon, Jan 24th 2011 by Strutynski.karol


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