Quasirandom distributed Gaussian bases for bound problems

We introduce quasirandom distributed Gaussian bases (QDGB) that are well suited for bound problems. The positions of the basis functions are chosen quasirandomly while their widths and density are functions of the potential. The basis function overlap and kinetic energy matrix elements are analytical. The potential energy matrix elements are accurately evaluated using few-point quadratures, since the Gaussian basis functions are localized. The resulting QDGB can be easily constructed and is shown to be accurate and efficient for eigenvalue calculation for several multidimensional model vibrational problems. As more demanding examples, we used a 2D QDGB-DVR basis to calculate the lowest 400 or so energy levels of the water molecule for zero total angular momentum to sub-wave-number precision. Finally, the lower levels of Ar-3 and Ne-3 were calculated using a symmetrized QDGB. The QDGB was shown to be accurate with a small basis. (C) 2001 American Institute of Physics.