HF

This method keyword requests a Hartree-Fock calculation. Unless explicitly specified, RHF is used for singlets and UHF for higher multiplicities. In the latter case, separate α and β orbitals will be computed [Roothaan51, Pople54, McWeeny68]. RHF, ROHF or UHF can also be specified explicitly.

Energies, analytic gradients, and analytic frequencies for RHF and UHF and numerical frequencies for ROHF.

The Hartree-Fock energy appears in the output as follows:

      SCF Done:  E(RHF) =  -74.9646569691     A.U. after    4 cycles
      Conv  =     0.48D-08          -V/T =  2.0038

For UHF jobs, the output also prints S² and related values:

 SCF Done:  E(UHF) =  -38.7068863059     A.U. after   11 cycles
             Convg  =    0.7647D-08             -V/T =  2.0031
 <Sx>= 0.0000 <Sy>= 0.0000 <Sz>= 1.0000 <S**2>= 2.0142 S= 1.0047
 <L.S>= 0.000000000000E+00
 Annihilation of the first spin contaminant:
 S**2 before annihilation     2.0142,   after     2.0001

The second and third lines give the SCF convergence limit and the expectation value of S².