A 3-DIMENSIONAL FINITE-ELEMENTS PROCEDURE FOR QUANTUM-MECHANICAL APPLICATIONS

We developed a general three-dimensional finite elements code for application to quantum mechanical problems. Instead of polynomials any set of numerically given functions can be used as local interpolation functions and the grid can be any arrangement of rectangular volumes. The importance of the choice of an adequate coordinate system is pointed out by comparison of Jacobi, hyperspherical and other coordinate systems. We present the examples of s-states of He and the muonic molecular ions td mu and dd mu. The flexibility of the code is demonstrated by reviewing two applications to lower-dimensional problems.