From owner-chemistry:~at~:ccl.net Fri Jun 8 15:19:00 2007 From: "Alex A. Granovsky gran###classic.chem.msu.su" To: CCL Subject: CCL:G: post-Hartree claculations, advice needed Message-Id: <-34445-070608113849-10312-SZDGs3U9aAzJvi84g0qBkQ- -server.ccl.net> X-Original-From: "Alex A. Granovsky" Content-Type: multipart/alternative; boundary="----=_NextPart_000_0075_01C7AA06.75FA4490" Date: Fri, 8 Jun 2007 19:51:52 +0400 MIME-Version: 1.0 Sent to CCL by: "Alex A. Granovsky" [gran+*+classic.chem.msu.su] This is a multi-part message in MIME format. ------=_NextPart_000_0075_01C7AA06.75FA4490 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dear Matthias, I would recommend PC GAMESS for very fast and memory efficient MP4 = calculations. Best regards, Alex Granovsky ----- Original Message -----=20 From: Matthias Gottschalk gottschalk~~gfz-potsdam.de=20 To: Granovsky, Alex, A. =20 Sent: Friday, June 08, 2007 12:35 PM Subject: CCL:G: post-Hartree claculations, advice needed Dear colleagues I hope that somebody could give me some advice. I want to calculate energies for dimers and trimers to extract = accurate potentials using post Hartree methods (also for "large" = distances > 5 Angstroms). I intend to do this for closed- and open-shell = systems (UHF) consisting of simple atoms (in the moment). Because I am not a computational chemistry specialist I did some = reading and as a result I concluded that methods like MP4, CCSD and = QCISD might be appropriate using a basis set like aug-cc-pVQZ might be = appropriate. I did success-full calculations for Ar dimers with gaussian g03 = reproducing published results which made me confident. I failed for = trimers using these evolved methods so long, however (might be due to = that I have only a 32 bit compiled version and the required real memory = exceeds 2.2 GB possible with 32 bit, I do have 8 GB, however). MP2 = trimers with more simple basis sets work, but that might be not what I = want? Now my questions are: 1. are the methods described above adequate? 2. which of the many programs available could be recommended to use? Thanks Matthias --=20 Prof. Dr. Matthias Gottschalk GeoForschungsZentrum Sektion 4.1 Telegrafenberg 14473 Potsdam Germany tel/fax +49 (0) 331 288-1418/1402 ------=_NextPart_000_0075_01C7AA06.75FA4490 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dear Matthias,
 
I would recommend PC GAMESS for very = fast and=20 memory efficient MP4 calculations.
 
Best regards,
Alex Granovsky
 
 
----- Original Message -----
From:=20 Matthias Gottschalk=20 gottschalk~~gfz-potsdam.de
To: Granovsky, Alex, A. =
Sent: Friday, June 08, 2007 = 12:35=20 PM
Subject: CCL:G: post-Hartree=20 claculations, advice needed

Dear colleagues

I hope that somebody could give me some advice.
I want to calculate energies for dimers and trimers to extract = accurate=20 potentials using post Hartree methods (also for "large" distances > = 5=20 Angstroms). I intend to do this for closed- and open-shell systems = (UHF)=20 consisting of simple atoms (in the moment).
Because I am not a computational chemistry specialist I did some = reading=20 and as a result I concluded that methods like MP4, CCSD and QCISD = might be=20 appropriate using a basis set like aug-cc-pVQZ might be = appropriate.
I did success-full calculations for Ar dimers with gaussian g03=20 reproducing published results which made me confident. I failed for = trimers=20 using these evolved methods so long, however (might be due to that I = have only=20 a 32 bit compiled version and the required real memory exceeds 2.2 GB = possible=20 with 32 bit, I do have 8 GB, however). MP2 trimers with more simple = basis sets=20 work, but that might be not what I want?

Now my questions are:

1. are the methods described above adequate?
2. which of the many programs available could be recommended to=20 use?

Thanks

Matthias

-- 

Prof. Dr. Matthias Gottschalk
GeoForschungsZentrum
Sektion 4.1
Telegrafenberg
14473 Potsdam
Germany

tel/fax  +49 (0) 331 288-1418/1402

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