Trransition Metal‐ and Actinide‐Containing Systems Studied with Multiconfigurational Quantum Chemical Methods

Abstract

Ab initio quantum chemistry has advanced so far in the last 40 years that it now allows the study of molecular systems containing any atom in the Periodic Table . Transition metal and actinide compounds can be treated routinely, provided that electron correlation 1 and relativistic effects 2 are properly taken into account. Computational quantum chemical methods can be employed in combination with experiment, to predict a priori, to confirm, or eventually, to refine experimental results. These methods can also predict the existence of new species, which may eventually be made by experimentalists. This latter use of computational quantum chemistry is especially important when one considers experiments that are not easy to handle in a laboratory, as, for example, explosive or radioactive species. It is clear that a good understanding of the chemistry of such species can be useful in several areas of scientific and technological exploration. Quantum chemistry can model molecular properties and transformations, and in

Approximate Analytical Gradients and Nonadiabatic Couplings for the State-Average Density Matrix Renormalization Group Self-Consistent-Field Method

“…Multiconfigurational methods are tailored for molecular systems exhibiting strong electronic correlation, as found in many transition metal complexes, − bond dissociation processes, and excited electronic states. ,− Excited electronic states are of key importance for photoinduced phenomena, including light–matter interaction with DNA, − light harvesting, photocatalysis and artificial photosynthesis, − as well as photodynamic cancer therapy. − …”

Assessing the Strength of Metal–Metal Interactions

“…k TM-TM(1) should be equal to 1.33 mdyn/Å for the Cr−Cr bond (like for the Cu−Cu bond) and 1.18 mdyn/Å for the Mo−Mo bond (like for the Ag−Ag bond). It means that the Cr−Cr bond should be more strong than the Mo−Mo one, while, according to the values of dissociation energy 10 and the size of atomic orbitals,11 the Mo−Mo bond is effectively stronger than the Cr−Cr one, in spite of the same formal BO. Similarly, the applicability of eq 2 with the same a and b constants for all TMs should be verified.…”