— —   Extension of the PS-GVB Electronic Structure Code to Transition Metal Complexes DANIEL T. MAINZ, 1 * JASNA J. KLICIC, 1 ‡ RICHARD A. FRIESNER, 1 JEAN-MARC LANGLOIS, 2 JASON K. PERRY 2 1 Department of Chemistry and Center for Biomolecular Simulation, Columbia University, 3000 Broadway, New York, New York 10027 2 Schrodinger, Inc., 121 SW Morrison, Suite 1212, Portland, Oregon 97204 ¨ Received 3 September 1996; accepted 20 June 1997 ABSTRACT: We have developed a parameterization enabling ab initio electronic structure calculation via the PS-GVB program on transition-metal- containing systems using two standard effective core potential basis sets. Results are compared with Gaussian-92 for a wide range of complexes, and superior performance is demonstrated with regard to computational efficiency for single-point energies and geometry optimization. Additionally, the initial guess strategy in PS-GVB is shown to provide considerably more reliable convergence to the ground state.  1997 John Wiley & Sons, Inc. J Comput Chem 18: 1863  1874, 1997 Keywords: electronic structure; transition metals; pseudospectral methods; Hartree  Fock theory; density functional theory Introduction he study of transition-metal-containing sys- T tems by ab initio quantum chemistry is a challenging and important area of electronic struc- Ž . *Present address: Beckman Institute 13974 , California In- stitute of Technology, Pasadena, CA 91125 ‡ Presently affiliated with Schrodinger, Inc. ¨ Correspondence to:R. A. Friesner Contractgrant sponsor: Department of Energy; contract grant number-DE-FG02-90ER-14162 ture theory. Transition metal systems are difficult to model with empirical force fields or semiempiri- cal methods, necessitating an ab initio approach. However, due to the fractional occupation of the d shells, a large number of near-degenerate states make electronic structure calculations difficult. Al- though there has been considerable progress in the application of both wave-function-based methods Ž . and density functional theory DFT to transition metals over the past decade, 1  3 there are still both quantitative and qualitative difficulties that are significantly greater than those for organic sys- tems. ( ) Journal of Computational Chemistry, Vol. 18, No. 15, 1863 1874 1997  1997 John Wiley & Sons, Inc. CCC 0192-8651 / 97 / 151863-12