arXiv subjects
Publications and source records attributed to Abdelrahman M. Ahmed.
Over the past decade, the Python-based Simulations of Chemistry Framework (PySCF) has developed into a widely used open-source platform for electronic structure theory and quantum chemical method development. This article reviews the major advances since the previous overview in 2020, covering new modules and methodology, infrastructure changes, and performance benchmarks.
We present the first-ever implementation and benchmark of periodic algebraic diagrammatic construction theory (ADC) for core-ionized states and X-ray photoelectron spectra (XPS) in crystalline materials. Using a triple-zeta Gaussian basis set and accounting for finite-size and scalar relativistic effects, the strict and extended second-order ADC approximations (ADC(2) and ADC(2)-X) predict the core ionization energies of weakly correlated solids within ~ 1.5 and 0.5 eV of experimental measurements, respectively. We further demonstrate that the ADC(2)-X method can capture the satellite features in XPS spectra of graphite, cubic and hexagonal boron nitride, and TiO2, albeit significantly overestimating their energies. The ADC(2)-X calculations reveal that the satellite transitions display strong configuration interaction with excitations involving several frontier orbitals delocalized in phase space. Our work demonstrates that ADC is a promising first-principles approach for simulating the core-excited states and X-ray spectra of materials, highlighting its potential and motivating further development.