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http://aliga.iciq.es/wiki/images/files/g98/index.htm
http://aliga.iciq.es/wiki/images/files/g98/index.htm
== Gaussian09 vs Gaussian03 Scaling and New Functional Testing ==
Tests calculations performed at the CESCA supercomputer on parallel8 queue (prades) with 14000MB ram.
'''Calcfc, opt to TS, and frequency.'''
Job has 687 basis functions with B3LYP method.
      Step           G03           G09
calcfc to 2nd l103 7h 54m 08s    3h 42m 10s
2nd opt step             8m 00s   9m 16s
3rd opt step             6m 06s   7m 06s
freq                 8h 30m 25s 4h 6m 15s
Total calc time        16h 38m 39s 8h 4m 47s
So the frequency calculation is about 2x faster in Gaussian09.
The SCF takes longer, but it is using the new GEDIIS algorithm (vs GDIIS in G03 which now doesn't exist).
They say GEDIIS should give better performance, especially for calculations not so close to convergence as this example.
'''Testing new functionals with G09'''
Job has 687 basis functions, starting structure from B3LYP method in G03.
      Step               Functional
    measured              M06         B97D
calcfc to 2nd l103    4h 49m 34s      1h 59m 42s
2nd opt step         13m 36s          7m 42s
3rd opt step         13m 37s          7m 15s
Total opt time     19h 05m 32s      3h 36m 35s
No. steps             89             32
avg opt step time     772s     406s
freq               5h 27m 59s      2h 11m 48s
Total calc time      29h 50m 18s      7h 48m 05s
The M06 functional is 33% slower than B3LYP (based on the frequency times), but still faster than B3LYP in G03.
Grimme's B97D functional is very fast, and also takes less steps to optimize in this case too.

Revision as of 16:01, 9 October 2009

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Gaussian 09 is the latest in the Gaussian series of electronic structure programs. Gaussian is used by chemists, chemical engineers, biochemists, physicists and others for research in established and emerging areas of chemical interest.

Starting from the basic laws of quantum mechanics, Gaussian predicts the energies, molecular structures, and vibrational frequencies of molecular systems, along with numerous molecular properties derived from these basic computation types. It can be used to study molecules and reactions under a wide range of conditions, including both stable species and compounds which are difficult or impossible to observe experimentally such as short-lived intermediates and transition structures. This article introduces several of its new and enhanced features.

GAUSSIAN was first written by John Pople and released in 1970. According to the manual, it can deal with different computational approaches: molecular mechanics (AMBER, UFF, DREIDING), semi-empirical calculations (AM1,PM3,CNDO,INDO,MINDO/3,MNDO), SCF methods (Restricted, Unrestricted, and Restricted Open-shell Hartree-Fock), Møller-Plesset perturbation theory, DFT methods (Hybrid functionals, exchange functionals and correlation functionals), ONIOM (QM/MM method), Complete Active Space (CAS) and Multi-Configurational Self-Consistent Field calculations, Coupled Cluster calculations, QCI methods and Quantum chemistry composite methods.

Nearly everything you need to know can be found on the Gaussian's homepage, 1 and the on-line manual, [2]]


Old version of Gaussian, G98

http://aliga.iciq.es/wiki/images/files/g98/index.htm