Metastable He2 and Its Autodetachment Spectra: An Accurate Coupled-Cluster Study.

摘要

The determination of the interaction energy of two helium atoms is a very old problem in quantum chemistry. Although most attention has been paid to the Van der Waals region, the repulsive part has also been investigated. Despite the small size of the He2 system quantum calculations, especially around the Van der Waals minimum, are very challenging. This is mainly due to the necessity of using extremely large and carefully optimized basis sets while employing very accurate quantum-mechanical methods. Furthermore, the basis-set superposition error (BSSE) is known to play a critical role in this case, and for many basis sets will be larger than the Van der Waals depth itself. (JES)