CCL:G: DFT and dispersion

 Sent to CCL by: Andras Borosy [andras.borosy%a%givaudan.com]
 You may find answers to your questions in
 Comprehensive Benchmarking of a Density-Dependent Dispersion Correction
 http://pubs.acs.org/doi/abs/10.1021/ct200602x
 Best wishes,
 Dr. AndrÃs PÃter Borosy
 Scientific Modelling Expert
 Fragrance Research
 Givaudan Schweiz AG  -  Ueberlandstrasse 138  -  CH-8600  -  DÃbendorf  -
 Switzerland
 T:+41-44-824 2164  -  F:+41-44-8242926    -  http://www.givaudan.com
 > From:	"Arne Dieckmann adieckma(-)googlemail.com"
             <owner-chemistry%ccl.net>
 To:	"Borosy, Andras " <andras.borosy%givaudan.com>
 Date:	28.10.2011 07:46
 Subject:	CCL:G: DFT and dispersion
 Sent by:	owner-chemistry+andras.borosy==givaudan.com%ccl.net
 Sent to CCL by: Arne Dieckmann [adieckma(-)googlemail.com]
 Dear Lars,
 thanks for your immediate reply. I know about the differences between the
 Minnesota functionals and the DFT-D3 method. This is why I wanted to
 augment their mid-range dispersion with the long range dispersion your
 former group developed. Do you know if TPSS with D-corrections produces
 significantly different geometries than M06-2X without D-corrections? How
 much do geometries of molecules (>= 50 atoms) change in general? I am just
 wondering if it will be sufficient to optimize with M06-2X and apply the
 single point D-corrections.
 By the way, do you know how well DFT-D3 works with implicit solvation? I
 guess in this case the parameters would have to be solvent-dependent,
 right?
 Thanks again,
 Arne
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Dr. Arne Dieckmann
 Houk Research Lab
 University of California, Los Angeles
 email: adieckma+*+googlemail.com
 On Oct 27, 2011, at 5:28 PM, Dr. Lars Goerigk lars.goerigk
 {}chem.usyd.edu.au wrote:
 >
 > Sent to CCL by: "Dr. Lars Goerigk"
 [lars.goerigk(~)chem.usyd.edu.au]
 > Dear Arne,
 >
 > M06-2X was fitted to noncovalently bound systems in their equilibrium
 geometries and due to that fit it somehow incorporates medium-range
 dispersion interactions. However, as also discussed in the literature, it
 is expected that the asymptotic long-range behavior is still not correct
 and that it can also benefit from dispersion corrections.
 > On the issue DFT-D3 in combination with the Minnesota functionals you can
 refer to PCCP 2011, 13, 6670. There, the parameters for DFT-D3 for those
 functionals were published and discussed.
 >
 > DFT-D2 parameters for the Minnesota functionals were published by the
 Martin group in JPCA 2008, 112, 12868. The s6 had to be smaller than unity,
 though, which still does not give the correct asymptotics, opposed to
 DFT-D3, where it was fixed to unity.
 >
 > If you have the Gaussian code available you could try to implement DFT-D3
 (based on the code Stefan Grimme made available on his website).
 > If you do not have the code, you would have to use DFT-D2. Please note
 that in G09 Rev A, DFT-D2 only works with B97-D and omega-B97X-D.
 > That bug was fixed however and in Rev. B01 and higher you can now also
 use DFT-D2 for those functionals, which are mentioned in Grimme's DFT-D2
 paper from 2006 (i.e. also for B3LYP, TPSS, PBE, BP86).
 > You have to use the IOp(3/124=3) then. In combination with IOp33(3=3) you
 also get a printout to check, if the correct s6 value was applied.
 > Other functionals are not supported and I do not know if it is possible
 to read in an s6 specified by the user (maybe you should contact the
 Gaussian support to find that out). IOp(3/124=1)  adds the dispersion
 correction to any functional, but only with an s6=1, which is too large for
 the Minnesota functionals.
 >
 > If you can't use M06-2X, you could try TPSS in combination with
 D-corrections. Based on publications and my own experience, this gives very
 good structures.
 >
 > Another possibility would be to get ORCA, which is for free. I am not
 100% sure if DFT-D3 is already implemented; have a look at the ORCA website
 for that.
 > You could also check if other programs have already implemented DFT-D3.
 >
 > I hope these information could help you.
 >
 > With best wishes,
 > Lars
 >
 > --
 > Dr. Lars Goerigk
 > School of Chemistry
 > The University of Sydney
 > Sydney, New South Wales 2006
 > Australiahttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt