TheMPnmethod keywords request a Hartree-Fock calculation (by default, RHF for singlets, UHF for higher multiplicities) followed by a Møller-Plesset correlation energy correction[Moller34], truncated at second-order forMP2[Head-Gordon88a,Saebo89,Frisch90b,Frisch90c,Head-Gordon94], third order forMP3[Pople76,Pople77], fourth-order forMP4[Raghavachari78], and fifth-order forMP5[Raghavachari90]. Analytic gradients are available for MP2[Pople79,Handy84,Frisch90b,Frisch90c], MP3 and MP4(SDQ)[Trucks88,Trucks88a], and analytic frequencies are available for MP2[Head-Gordon94]. ROMP2, ROMP3 and ROMP4 energies are also available[Knowles91,Lauderdale91,Lauderdale92].
Gaussian 09 also includes some double hybrid methods which combine exact HF exchange with an MP2-like correlation to a DFT calculation. These methods have the same computational cost as MP2 (rather than that of DFT). Gaussian 09 includes Grimme’s B2PLYP[Grimme06a]and mPW2PLYP[Schwabe06]methods(via keywords of the same name); the empirical dispersion corrected variations are specified by appending aDto the keyword name: e.g.,B2PLYPDforB2PLYPwith empirical dispersion[Schwabe07].B2PLYPD3requests the same but with Grimme's D3BJ dispersion[Grimme11,Goerigk11]. Energies, gradients and frequencies are available.
MP4(DQ)is specified to use only the space of double and quadruple substitutions,MP4(SDQ)for single, double and quadruple substitutions, orMP4(SDTQ)for fullMP4with single, double, triple and quadruple substitutions[Raghavachari78,Raghavachari80]. Just specifyingMP4defaults toMP4(SDTQ).
The MP5 code has been written for the open shell case only, and so specifyingMP5defaults to aUMP5calculation. This method requires O3V3disk storage and scales as O4V4in cpu time.
FC
All frozen core options are available with this keyword. See the discussion of theFCoptions for full information.
The appropriate algorithm forMP2will be selected automatically based on the settings of%MemandMaxDisk. Thus, the following options are almost never needed.
FullDirect
Forces the fully direct algorithm, which requires no external storage beyond that for the SCF. Requires a minimum of2OVNwords of main memory (O=number of occupied orbitals,V=number of virtual orbitals,N=number of basis functions). This is seldom a good choice, except for machines with very large main memory and limited disk.
SemiDirect
Forces the semi-direct algorithm.
Direct
Requests some sort of direct algorithm. The choice between in-core, fully direct and semidirect is made by the program based on memory and disk limits and the dimensions of the problem.
InCore
Forces the in-memory algorithm. This is very fast when it can be used, but requiresN4/4 words of memory. It is normally used in conjunction withSCF=InCore.NoInCoreprevents the use of the in-core algorithm.
MP2,B2PLYP[D],mPW2PLYP[D] : Energies, analytic gradients, and analytic frequencies.
MP3,MP4(DQ)andMP4(SDQ): Energies, analytic gradients, and numerical frequencies.
MP4(SDTQ)andMP5: Analytic energies, numerical gradients, and numerical frequencies.
ROmay be combined withMP2,MP3andMP4for energies only.
Energies.The MP2 energy appears in the output as follows, labeled asEUMP2:
E2= -.3906492545D-01 EUMP2= -.75003727493390D+02
Energies for higher-order Møller-Plesset methods follow. Here is the output from an MP4(SDTQ) calculation:
Time for triples= .04 seconds. MP4(T)= -.55601167D-04 E3= -.10847902D-01 EUMP3= -.75014575395D+02 E4(DQ)= -.32068082D-02 UMP4(DQ)= -.75017782203D+02 E4(SDQ)= -.33238377D-02 UMP4(SDQ)= -.75017899233D+02 E4(SDTQ)= -.33794389D-02UMP4(SDTQ)= -.75017954834D+02
The energy labeledEUMP3is the MP3 energy, and the various MP4-level corrections appear after it, with the MP4(SDTQ) output coming in the final line (labeledUMP4(SDTQ)).
Example B2PLYP Output.TheB2PLYPenergy appears in the output labeled asE(B2PLYP):
E2(B2PLYP) = -0.3262340664D-01 E(B2PLYP) = -0.39113226645200D+02
Last update: 26 June 2013