CAREER: Enabling the Accurate Simulation of Multi-Dimensional Core-Level Spectroscopies in Molecular Complexes using Time-Dependent Density Functional Theory

University Of Memphis, Memphis TN

Investigators

Abstract

With support from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry, Dr. Daniel Nascimento of the University of Memphis is developing computational approaches to simulate how molecules interact with X-rays. These simulations provide valuable information on how molecules behave, and by extension, how they can be used and manipulated in technological applications relevant to medicine, materials science, engineering, and environmental chemistry. Dr. Nascimento and his research group will develop cost-effective algorithms to simulate multi-dimensional X-ray spectroscopies that will enable a better understanding of molecular systems relevant for the development of novel materials and technologies. These algorithms will be implemented as part of the Psi4 electronic structure package, an open-source, state-of-the-art quantum chemistry software package freely available to the chemistry community. As part of outreach and educational efforts, Dr. Nascimento will launch a summer program in computational chemistry targeting undergraduate students from across the Mid-South region. These efforts are designed to impact the recruitment and development of future theoretical and computational chemists and are seen as a vehicle to work toward building a diverse, talented future workforce for the field. Recent advancements in X-ray free-electron laser (XFEL) technologies have opened up new avenues for conducting multi-dimensional core-level spectroscopy experiments at high energies. However, to effectively interpret and make sense of the vast amount of data generated by these facilities, it is imperative to have precise theoretical models that can faithfully replicate the underlying processes. Current models employed in the interpretation of experimental X-ray data are either too simplified to be predictive or entail extensive computations that are practical only for relatively small molecules. Dr. Nascimento and his research group are taking a novel approach by harnessing the principles of response theory to develop, implement, and apply cost-effective algorithms for simulating multi-dimensional core-level spectroscopies in real-world systems, featuring around 100 to 150 atoms. These algorithms will be integrated into the Psi4 electronic structure package. Through this research effort, Dr. Nascimento aims to deepen our understanding of several critical aspects, including the significance of second-order relaxation effects in calculating excited-state transition moments in molecular complexes, the utilization of quasi-degenerate perturbation theory to introduce spin-orbit coupling effects into these transition moments, and the development of a state-specific strategy for addressing dissipation channels with minimal parameterization. The algorithms and computer programs resulting from this project are expected to enhance the ways in which multi-dimensional X-ray spectroscopy simulations are performed and to increase the reach and predictive ability of computational chemistry in the new era of XFEL-driven science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.