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LHF

To run a LHF calculations select:
$dft
   functional lhf
   gridsize   3

This can be done using define (modified grid are not supported) and then run odft.

A more suitable procedure is the following:

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. Actually LHF can be started from any guessed orbitals, but if HF orbitals are used, a much faster convergence is expected. By default the script lhfprep will add/modify the control file with:
$dft
   functional lhf
   gridtype   6
   gridsize   3
   radsize    3
$lhf
   off-diag on
   num-slater off
   asymptotic dynamic=1.d-3
   conj-grad conv=1.d-6 maxit=20 output=1 asy=1
   slater-dtresh 1.d-9
   slater-region     7.0 0.5 10.0 0.5
   corrct-region             10.0 0.5
$scfdump
$scfiterlimit 30
$scfconv 6
$scfdamp start=0.000 step=0.500 min=0.50
$scforbitalshift noautomatic
$correction matrix-elements file=lhfcg
$correction alpha matrix-elements file=lhfcg_alpha
$correction beta matrix-elements file=lhfcg_beta
3)
Run odft.

With the LHF potential Rydberg series of virtual orbitals can be obtained. To that end, diffuse orbital basis sets have to be used and special grids are required.

gridtype 4 is the most diffuse with special radial scaling; gridtype 5 is for very good Rydberg orbitals; gridtype 6 (default in Lhfprep) is the least diffuse, only for the first Rydberg orbitals.

Only gridsize 3-5 can be used, no modified grids.

Use test-integ to check if the selected grid is accurate enough for the employed basis-set, see page [*].

The options in the $lhf group are:

off-diag on

The LHF exchange potential is computed (default);
off-diag off

The KLI exchange potential is computed (can be selected by lhfprep -kli).
num-slater on

the Slater potential is calculated numerically everywhere: this is more accurate but quite expensive. When ECPs are used, turn on this option. It can be selected by lhfprep -num.
num-slater off

the Slater potential is computed using basis-sets. This leads to very fast calculations, but accurate results are obtained only for first-row elements or if an uncontracted basis set or a basis set with special additional contractions is used. This is the 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. It can be selected by lhfprep -asy.
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.
For other options see 18.2.6.


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Next: How to plot the Up: How to Perform Previous: OEP-EXX   Contents   Index
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