Fast computation of analytical second derivatives with effective core potentials: Application to Si_8C_(12), Ge_8C_(12), and Sn_8C_(12)

摘要

An improved method is described for the computation of integrals involving effective core potentials. The improved method provides better scalability to higher angular momenta as well as improved speed. The new method is also applied to the determination of the minimum energy structures of Si_8C_(12), Ge_8C_(12), and Sn_8C_(12), main group analogs of the Ti_8C_(12) compounds (known as metcars). Relative energies, geometries, and vibrational frequencies are reported for several novel structures.