However, such non-covalent bonds and interactions can be inferred from other NBO-reported quantities. Specifically, to identify metal coordinate bonds, we examine NBO's second-order perturbation theory analysis of the Fock matrix. If there is an interaction between a lone pair ("LP") orbital on a nonmetal (donor) and a lone vacant ("LV") or anti-Rydberg orbital ("RY*") on a metal (acceptor) where the metal is within 3.0 Å of the nonmetal and the perturbation energy is greater than or equal to 3.0 kcal/mol, then we determine the metal and nonmetal to be electrostatically bonded. These cutoff values were determined by manual inspection of set of metal-containing complexes and are, like most definitions of bonding, arbitrary.