genfrag

Contents

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

General keywords

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

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.

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.

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

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

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

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

xxx

Filename	Description	Format

You can insert latex formula as

$\begin{equation} \rho_{\mu}=\sum_i w_i*\chi_{\mu}(r_i)\chi_{\mu}(r_i) \end{equation}$

You can also insert a latex formular inline