The program mpshift calculates nuclear magnetic shielding constants using the GIAO (Gauge Including Atomic Orbital) method.

At present the following methods are implemented:

HF-SCF

the coupled perturbed Hartree–Fock (CPHF) equations in the AO basis are solved using a semi-direct iterative algorithm [164] similar to dscf.

DFT

using either non-hybrid functionals where no iterations are needed [165] or hybrid functionals where the same algorithm as at the HF-SCF level is used.

MP2

semi-direct method, see ref.  [25].