Relativistic corrections:

$mvd leads to calculation of relativistic corrections for the SCF total density in case of dscf and ridft, for the SCF+MP2 density in case of rimp2 and mpgrad and for that of the calculated excited state in case of egrad. Quantities calculated are expectation values < p² > , < p⁴ > and the Darwin term ( $\sum$1/Z_A*ρ(R_A)). Note, that at least the Darwin term requires an accurate description of the cusp in the wave function, thus the use of basis sets with uncontracted steep basis functions is recommended. Moreover note, that when using of ECPs these quantities are not too reasonable (a respective warning is written to the output).