@article{Multiconfiguration:5214,
      recid = {5214},
      author = {Scott, Thaïs Renee},
      title = {Multiconfiguration Pair-Density Functional Theory  Developments and Applications to Photo-chemically Relevant  Excited States},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2022-12},
      pages = {148},
      abstract = {The primary focus of this research is the development and  application of cost efficient multirefer-ence methods to  quantitatively model chemical phenomena in excited  states.
Multi-configuration pair-density functional theory  (MC-PDFT) is a method developed in the
Gagliardi and  Truhlar groups that aims at combining the advantages of  wave function and density
functional theories to allow  robust modeling of strongly correlated systems. While the  energies
of MC-PDFT with a state-average reference have  shown remarkable accuracy for reaction barriers
and  excitation energies, analytic gradients are necessary for  additional applications like efficient
calculations of  stationary points on potential energy surfaces and direct  dynamics simulations.
The analytic gradients for MC-PDFT  with a state-average reference wave function and  density
fitting were implemented in the OpenMolcas and  PySCF software. Including density fitting made
the code  more performant and allowed for the study of significantly  larger systems. This was then
extended by formulating and  implementing gradients and energies for compressed  multi-state pair-
density functional theory (CMS-PDFT).  CMS-PDFT includes state interactions by allowing states
to  mix through the diagonalization of an effective  Hamiltonian. As a result, this method gives the
correct  shape of the potential energy surface for systems with  nearly degenerate states, e.g., near
conical intersections  or locally avoided crossings.
In this work, we are  interested in photosensitization, which is a process where  a light-harvesting
molecule transfers energy to a substrate  and promotes it to an excited state. This excitation  mech-
anism is important for the photochemistry of Ir-Ni  dual catalysis and photolesion formation  in
thio-substituted DNA. In both studies, the insights  provided by the MC-PDFT calculations helped
to determine  the mechanism responsible for these photochemical  reactions.

},
      url = {http://knowledge.uchicago.edu/record/5214},
      doi = {https://doi.org/10.6082/uchicago.5214},
}