Toyota03

K. Toyota, I. Mayumi, M. Ehara, M. J. Frisch, and H. Nakatsuji, “Singularity-free analytical energy gradients for the SAC/SAC-CI method: Coupled perturbed minimum orbital-deformation (CPMOD) approach,” Chem. Phys. Lett., 367 (2003) 730-36. DOI: 10.1016/S0009-2614(02)01629-9