Calculation of molecular integrals for systems confined by hard spherical walls: Use of the single-center expansion of floating spherical gaussians

Assuming a gaussian basis set representation of atomic and molecular wave f unctions, the single-center expansion of off-centered spherical gaussian or bitals is exploited to calculate the one and two-electron integrals for mul tielectronic atoms and molecules confined within hard spherical walls. As a validating test, the ground-state energy of a helium atom positioned off-c enter in a spherical box is calculated by applying the simplest form of the floating spherical gaussian orbital (FSGO) scheme, i.e., the use of a prim itive basis set consisting of a single FSGO per electron pair. Comparison w ith corresponding recent accurate calculations gives supporting evidence of the adequacy of the method for its application to more elaborate gaussian- type basis set representations for confined atoms and molecules. (C) 2001 J ohn Wiley & Sons, Inc. Int J Quantum Chem 83: 271-278, 2001.