The dipole moment, static polarizability and hyperpolarizabilities of
hydrogen peroxide, H2O2, have been determined in large-scale ab initio
calculations using the coupled cluster method, CCSD(T). The dependenc
e of the calculated properties on the torsional HOOH angle is discusse
d. At the CCSD(T)/aug-cc-pVTZ level of theory, the leading terms in th
e expansion of the dipole moment and mean polarizability in terms of t
he torsional angle are found to be 1.2062 and 15.04 au, respectively,
in good agreement with experiment. The transition dipole moments betwe
en various torsional energy levels are calculated and compared with re
cent experimental data.