A vibrational electronic-thermofield coupled cluster (VE-TFCC) approach is developed to
calculate thermal properties of non-adiabatic vibronic coupling systems. The thermofield …

Wave function methods have offered a robust, systematically improvable means to study
ground-state properties in quantum many-body systems. Theories like coupled cluster and …

We use full configuration interaction and density matrix quantum Monte Carlo methods to
calculate the electronic free energy surface of the nitrogen dimer within the free-energy Born …

We present a machine learning approach to calculating electronic specific heat capacities
for a variety of benchmark molecular systems. Our models are based on data from density …

The study of nuclei at finite temperature is of immense interest for many areas of nuclear
astrophysics and nuclear-reaction science. A variety of ab initio methods are now available …

Finite-temperature many-body perturbation theory in the grand-canonical ensemble is
fundamental to numerous methods for computing electronic properties at nonzero …

The density matrix quantum Monte Carlo (DMQMC) set of methods stochastically samples
the exact N-body density matrix for interacting electrons at finite temperature. We introduce a …

Molecules are often naturally embedded in a complex environment. As a consequence,
characteristic properties of a molecular subsystem can be substantially altered or new …

This thesis presents the development of two approaches—thermal normal-ordered
exponential (TNOE) and thermofield coupled cluster (TFCC)—for simulating quantum …

Wave function methods have offered a robust, systematically improvable means to study the
ground-state properties in quantum many-body systems. Theories like coupled cluster and …