genfrag

Module genfrag is used to generate molecular fragments and also fragment pairs that are used in Frag-MP2/CCSD calculation.

General keywords

optfrag

• Ask for fragment optimization. Next line is a string "all" or a list of fragments need to be optimized.

decfrag

• Fragments in DEC-(divide-expend-consolidate) MP2/CCSD proposed by Paul Jogensen et. al. are generated. If this keyword is not used in input. FragMP2 fragments will be generated.

threshrad

• For Frag-MP2, the following line is a float number to specify threshold of buffer radii in FragMP2. Default: 4.5 angstrom. For DEC-MP2, the following line is three float numbers to specify thresholds of virtual EOS space, occupied buffer space and unoccupied buffer space. Default: 4.5 3.0 1.5 angstrom. If fragment optimization is required, these threshold are used as initial thresholds.

threshtail

• The following line is two float numbers to define threshold of Coulomb tails of occupied and virtual orbitals. Default: 0.01 0.01.

threshextvir

• Threshold of extra virtual orbital in Frag-MP2/CCSD approach. Large value will add more extra virtual orbital in amplitude space. Default: 0.1.

distpair

• Threshold of distance pairs. Two fragment with distance larger than "dispair" will be neglect in correlation energy calculation. Default: 15 angstrom.

energy

• Set the method will be used in correlation calculation. Now, we only support MP2.

Expert keywords

noenergy

• Do not evoke energy calculation automatically.

fragpair

• Only generate fragment pairs. All punch files of fragments should be generated previously and saved in BDF_WORKDIR.

nopair

• Do not calculate interaction energy of between the fragment pairs.

Depend Files

Examples