How to do LHF runs

1)

Do a Hartree-Fock calculation using dscf.

2)

Use the script lhfprep to prepare the control file (the old control file will be saved in control.hf and the molecular orbitals in mos.hf or in alpha.hf and beta.hf for the spin-unrestricted case). See lhfprep -help for options.

3)

Run again dscf.

Otherwise the LHF functional can be selected in define: in this case default options are used.

Options for the LHF potential can be specified as follows ( see also lhfprep -help)

$lhf
   off-diag    on
   numerical-slater off
   pot-file save
   asymptotic dynamic=1.d-3
   homo     1b1u
   homob    1b1u    # ONLY UNRESTRICTED
   conj-grad conv=1.d-7 maxit=20 output=1 cgasy=1
   slater-dtresh    1.d-9
   slater-region     7.0 0.5 10.0 0.5
   corrct-region             10.0 0.5
   slater-b-region   7.0 0.5 10.0 0.5 # ONLY UNRESTRICTED
   corrct-b-region           10.0 0.5 # ONLY UNRESTRICTED
   correlation func=lyp

off-diag off

calculation of the KLI exchange potential. By default the LHF exchange potential is computed (off-diag on).

numerical-slater on

the Slater potential is calculated numerically everywhere: this is more accurate but much more expensive. When ECP are used, turn on this option.

numerical-slater off

leads to accurate results only for first-row elements or if an uncontracted basis set or a basis set with special additional contractions is used: in other cases numerical-slater on has to be used (this is default).

asymptotic

for asymptotic treatment there are three options:

asymptotic off

No asymptotic-treatment and no use of the numerical Slater. The total exchange potential is just replaced by -1/r in the asymptotic region. This method is the fastest one but can be used only for the density-matrix convergence or if Rydberg virtual orbitals are of no interest.

asymptotic on

Full asymptotic-treatment and use of the numerical Slater in the near asymptotic-region.

asymptotic dynamic=1.d-3

Automatic switching on (off) to the special asymptotic treatment if the differential density-matrix rms is below (above) 1.d-3. This is the default.

pot-file save

the converged Slater and correction potentials for all grid points are saved in the files slater.pot and corrct.pot, respectively. Using pot-file load, the Slater potential is not calculated but read from slater.pot (the correction potential is instead recalculated). For spin unrestricted calculations the corresponding files are slaterA.pot, slaterB.pot, corrctA.pot and correctB.pot.

homo

allows the user to specify which occupied orbital will not be included in the calculation of correction potential: by default the highest occupied orbital is selected. This option is useful for those systems where the HOMO of the starting orbitals (e.g. EHT, HF) is different from the final LHF HOMO. homob is for the beta spin.

correlation func=functional

a correlation functional can be added to the LHF potential: use func=lyp for LYP, or func=vwn for VWN5 correlation.