ATOMS AND MOLECULES IN CAVITIES - A METHOD FOR STUDY OF SPATIAL CONFINEMENT EFFECTS

A general method for solving the problems of spatially confined quantu m mechanical systems is proposed. The method works within the framewor k of the model space approximation. In the case of atoms and molecules trapped into any-shape microscopic cavity (like molecular sieves or f ullerenes), the method reduces to a simple modification of the commonl y used basis-set quantum chemical calculations. The modification consi sts of a particular rotation and projection in the model space, leadin g to solutions better adapted to the boundary conditions of the spatia l confinement than the functions that describe the free systems. To il lustrate how this method works, it has been applied to the hydrogen at om confined in a spherical well, near a hard wall and confined in a cu bic box. The results are also compared to the exact solutions. (C) 199 5 John Wiley & Sons, Inc.