Transition metal silicides are promising materials for improved electronic devices, and this motivates achieving a better understanding of transition metal bonds to silicon. Here we model the ground and excited state bond dissociations of VSi, NbSi, and TaSi using a complete active space (CAS) wave function and a separated-pair (SP) wave function combined with two post-self-consistent field techniques: complete active space with perturbation theory at second order and multiconfiguration pair-density functional theory. The SP approximation is a multiconfiguration self-consistent field method with a selection of configurations based on generalized valence bond theory without the perfect pairing approximation. For both CAS and SP, the active-space composition corresponds to the nominal correlated-participating-orbital scheme. The ground state and low-lying excited states are explored to predict the state ordering for each molecule, and potential energy curves are calculated for the ground state to compare to experiment. The experimental bond dissociation energies of the three diatomic molecules are predicted with eight on-top pair-density functionals with a typical error of 0.2 eV for a CAS wave function and a typical error of 0.3 eV for the SP approximation. We also provide a survey of the accuracy achieved by the SP and extended separated-pair approximations for a broader set of 25 transition metal–ligand bond dissociation energies.
Bibliographical noteFunding Information:
Funding: The present work was supported by the Air Force Office of Scientific Research under grant FA9550-16-1-0134.
The present work was supported by the Air Force Office of Scientific Research under grant FA9550-16-1-0134. The authors are grateful to Prachi Sharma for putting the OreLYP functional into OpenMolcas. The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing computational resources.
Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Complete-active space self-consistent field
- Kohn-Sham density functional theory
- Perturbation theory
- Potential energy surfaces
- Transition metals
PubMed: MeSH publication types
- Journal Article