From owner-nwchem-users@emsl.pnl.gov Thu Sep 2 11:42:42 2004 Received: from odyssey.emsl.pnl.gov (localhost [127.0.0.1]) by odyssey.emsl.pnl.gov (8.12.10/8.12.10) with ESMTP id i82IggcF013662 for ; Thu, 2 Sep 2004 11:42:42 -0700 (PDT) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.12.10/8.12.10/Submit) id i82IggfW013661 for nwchem-users-outgoing; Thu, 2 Sep 2004 11:42:42 -0700 (PDT) Date: Thu, 02 Sep 2004 11:42:39 -0700 From: Paul Ha-Yeon Cheong Subject: Summary: NWChem MP2 results different from Gaussian03 MP2 To: nwchem-users@emsl.pnl.gov Cc: Paul Ha-Yeon Cheong Message-id: MIME-version: 1.0 (Apple Message framework v619) X-Mailer: Apple Mail (2.619) Content-type: multipart/alternative; boundary=Apple-Mail-1--120757757 Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk --Apple-Mail-1--120757757 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; format=flowed Dear folks, Thank you very much for your responses, Pablo Vitoria, David Dixon, Robert Harrison, and So Hirata. The following is a summary of the question and the responses I received. The original question was: I ran MP2 single points jobs at the same basis set with NWChem and Gaussian03. However, the MP2 energies are quite different even though the geometries are exactly the same (copy, paste, verified). Is there a reason why the energies are different? Does NWChem do something different in calculating the SCF and/or MP2 compared to Gaussian? How can I run the NWChem calculations to get consistent results with Gaussian? -------- NWChem INPUT: -------- basis spherical * library 6-31G* end scf thresh 1.0e-8 end task mp2 ====== Result of NWChem MP2 calculation: ====== "Total SCF energy = -974.008605304341" "Total MP2 energy -977.059895142115" MP2 correction = 3.05128983777" -------- Gaussian03 INPUT: -------- #mp2/6-31g(d) guess=read geom=check ====== Result of Gaussian03 MP2 calculation: ====== "E2 = -0.3029098694D+01 EUMP2 = -0.97704154287316D+03" The responses to the above questions were: 1. HF SCF energies are different because the specified basis sets in the respective inputs were different from each other. Gaussian03 uses cartesian basis sets, while I have specified the use of spherical basis sets in NWChem. One can get consistent results from both programs by either specifying "basis cartesian" instead of "basis spherical" the NWChem input or specify 5D functions in the Gaussian03 input. 2. The MP2 perturbation energies are different because the number of orbitals included in the correlation are different for both programs. In Gaussian, specifying MP2 defaults to freezing the core orbitals, while in NWChem, MP2 signifies full correlation. In order to get the same energies, one can either specify "MP2(full)/6-31G*" in the Gaussian03 input or specify "freeze atomic" in the MP2 directive of an NWChem input. Best regards, Paul. _______________________________________ Paul Ha-Yeon Cheong Member of the K. N. Houk Group Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive, East Los Angeles, CA 90095 --Apple-Mail-1--120757757 Content-Transfer-Encoding: 7bit Content-Type: text/enriched; charset=US-ASCII Dear folks, Thank you very much for your responses, Pablo Vitoria, David Dixon, Robert Harrison, and So Hirata. The following is a summary of the question and the responses I received. The original question was: I ran MP2 single points jobs at the same basis set with NWChem and Gaussian03. However, the MP2 energies are quite different even though the geometries are exactly the same (copy, paste, verified). Is there a reason why the energies are different? Does NWChem do something different in calculating the SCF and/or MP2 compared to Gaussian? How can I run the NWChem calculations to get consistent results with Gaussian? -------- NWChem INPUT: -------- basis spherical * library 6-31G* end scf thresh 1.0e-8 end task mp2 ====== Result of NWChem MP2 calculation: ====== "Total SCF energy = -974.008605304341" "Total MP2 energy -977.059895142115" MP2 correction = 3.05128983777" -------- Gaussian03 INPUT: -------- #mp2/6-31g(d) guess=read geom=check ====== Result of Gaussian03 MP2 calculation: ====== "E2 = -0.3029098694D+01 EUMP2 = -0.97704154287316D+03" The responses to the above questions were: 1. HF SCF energies are different because the specified basis sets in the respective inputs were different from each other. Gaussian03 uses cartesian basis sets, while I have specified the use of spherical basis sets in NWChem. One can get consistent results from both programs by either specifying "basis cartesian" instead of "basis spherical" the NWChem input or specify 5D functions in the Gaussian03 input. 2. The MP2 perturbation energies are different because the number of orbitals included in the correlation are different for both programs. In Gaussian, specifying MP2 defaults to freezing the core orbitals, while in NWChem, MP2 signifies full correlation. In order to get the same energies, one can either specify "MP2(full)/6-31G*" in the Gaussian03 input or specify "freeze atomic" in the MP2 directive of an NWChem input. Best regards, Paul. Futura3939,3939,3939_______________________________________ Paul Ha-Yeon Cheong Member of the K. N. Houk Group Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive, East Los Angeles, CA 90095 --Apple-Mail-1--120757757--