Fully numerical mesh solution of 2D and 3D quantum equations of Schroedinger and Hartree-Fock type allows us to work with wavefunctions which have much more flexible geometry than wavefunctions in traditional basis-set approaches. This flexibility is especially important for calculations of atoms and molecules in strong external fields where neither the external field nor the internal interactions can be considered as a perturbation. The applications of the present approach include calculations of atoms and diatomic molecules in strong static electric and magnetic fields. For the magnetic fields we provide Hartree-Fock calculations for He, Li, Be, C [1-4] and some other atoms. This allowed us in particular to carry out the first comprehensive investigation of the ground state configurations of the Li [3] and C [4] atoms in the whole range of magnetic fields (0<B<10000 a.u.) and to study the ground state electronic configurations of all the atoms with 1<=Z<=10 and their ions A+ in the high-field fully spin-polarized regime [5]. The results on strong electric fields relate to single-electron systems including the correct solution of the Schroedinger equation for the (H2)+ ion (energies and decay rates) [6-7]. Incorporating many configurations into the numerical scheme enables us to perform the analoguous calculations for multi-electron systems: we provide an outline of the helium atom in strong electric fields [8].
[1] M.V. Ivanov, J. Phys. B: At. Mol. Opt. Phys., 27, 4513 (1994)
[2] M.V. Ivanov, Phys. Lett. A, 239, 72 (1998)
[3] M.V. Ivanov and P. Schmelcher, Phys. Rev. A, 57, 3793 (1998)
[4] M.V. Ivanov and P. Schmelcher, Phys. Rev. A, 60, 3558 (1999)
[5] M.V. Ivanov and P. Schmelcher, Phys. Rev. A, 61, 022505 (2000)
[6] M.V. Ivanov, Optika i Spectroskopiya, 76, 711 (1994)
[7] M.V. Ivanov, J. Phys. B: At. Mol. Opt. Phys., 31, 2833 (1998)
[8] M.V. Ivanov and P. Schmelcher, to be published