DRF input

To run a DRF calculation two block keys, DRF and EXTERNALS, are required. The DRF key controls the general options and the EXTERNALS key provides the atomic data for the MM atoms. The DRF key should not be used in combination with: COSMO, QM/MM, geometry optimization, frequency calculation or point charges.

A DRF calculation are invoked by the following block key DRF:

DRF
 {NORESP}
 {NOPOL}
 {NOCHAR}
 {LOCALFIELD}
 {EFIELD ex ey ez &}
 {AFAC a}
end

NORESP

DRF is ignored in RESPONSE and EXCITATION

NOPOL

The many-body operator is ignored (no induced dipoles)

NOCHAR

The Coulomb operator is ignored (no charges)

LOCALFIELD

Local Fields are included

EFIELD

Homogeneous external electric field is included. ex value of field in x-direction, ey value of field in y-direction, and ez value of field in z-direction. A continuation symbol, &, is required. The units are atomic units.