Møller–Plesset perturbation theory (MP2)

Description

Second-order Møller–Plesset perturbation theory (MP2) calculations are performed with density fitting using the keyword "title" : "mp2".

Keywords

frozen

Description: to have frozen orbitals or not
Datatype: bool
Default: true

ncore

Description: manually specify number of frozen orbitals, used when ‘frozen’ is turned on
Datatype: int

aux_basis

Description: specify an auxiliary basis set for MP2
Datatype: string
Default: use the same density fitting basis as in Required keywords
Recommendation: use MP2-fit auxiliary basis (auxiliary basis ends with ‘ri’)

Example

{ "bagel" : [

{
  "title" : "molecule",
  "basis" : "cc-pvdz",
  "df_basis" : "cc-pvdz-jkfit",
  "angstrom" : "true",
  "geometry" : [
    { "atom" : "C", "xyz" : [ -1.20433891360,  0.54285096106, -0.04748199659] },
    { "atom" : "C", "xyz" : [ -1.20543291352, -0.83826393986,  0.12432899108] },
    { "atom" : "C", "xyz" : [ -0.00000600000, -1.52953889027,  0.20833398505] },
    { "atom" : "C", "xyz" : [  1.20544091352, -0.83825393987,  0.12432799108] },
    { "atom" : "C", "xyz" : [  1.20433091360,  0.54284396106, -0.04748099659] },
    { "atom" : "C", "xyz" : [  0.00000400000,  1.23314191154, -0.13372399041] },
    { "atom" : "H", "xyz" : [ -2.13410484690,  1.07591192282, -0.12500499103] },
    { "atom" : "H", "xyz" : [ -2.13651384673, -1.37179190159,  0.18742198655] },
    { "atom" : "H", "xyz" : [  0.00000000000, -2.59646181374,  0.33932597566] },
    { "atom" : "H", "xyz" : [  2.13651384673, -1.37179290159,  0.18742198655] },
    { "atom" : "H", "xyz" : [  2.13410684690,  1.07591292282, -0.12500599103] },
    { "atom" : "H", "xyz" : [ -0.00000000000,  2.29608983528, -0.28688797942] }
  ]
},

{
  "title" : "hf"
},

{
  "title" : "mp2",
  "aux_basis" : "cc-pvdz-ri",
  "frozen" : true
}

]}

The SCF calculation should converge after 11 iterations with energy -230.72159477. The DF-MP2 output is as follows:

=== DF-MP2 calculation ===

  * freezing 6 orbitals
Number of auxiliary basis functions:      420

Since a DF basis is specified, we compute 2- and 3-index integrals:
  o Being stored without compression. Storage requirement is 0.044 GB
     - 3-index ints prep                         0.00
     - 3-index ints                              0.06
     - 2-index ints                              0.00
     - computing inverse                         0.02
      elapsed time:        0.09 sec.


Number of basis functions:      114
Number of electrons      :       42

  * 3-index integral transformation done
  * ncache = 20
  * assembly done

    MP2 correlation energy:   -0.7813195576      0.19

    MP2 total energy:       -231.5029143295


  * METHOD: MP2                                  0.34

References

Description of Reference Reference
Original reference for MP2 C. Møller and M. S. Plesset, Phys. Rev. 46, 618 (1934).