Periodic X-ray restrained wavefunctions for accurate determinations of optoelectronic properties of materials (XRWOptoMat)

Objective

The XRWOptoMat project introduces a groundbreaking extension of the X-ray restrained wavefunction (XRW) method to periodic systems, enabling the first quantum-mechanical determination of experimental wavefunctions for crystalline materials. By implementing this novel periodic XRW approach in the Crystal23 software package, we establish a transformative framework that directly combines X-ray diffraction experiments with ab initio quantum mechanics. This methodology achieves three key advances: (1) development of a periodic XRW formalism that maintains translational symmetry while optimizing wavefunctions against experimental structure factors; (2) implementation of coupled-perturbed XRW (CP-XRW) equations for predicting optical properties from the experimentally-constrained wavefunction; and (3) creation of a finite-field XRW protocol to extract environment-modified atomic polarizabilities. The project rigorously validates these methods using benchmark molecular crystals with well-characterized optical responses, demonstrating how experimental diffraction data can refine and enhance quantum mechanical predictions. Hosted at Politecnico di Milano under the supervision of Prof. Alessandro Genoni, this research pioneers a new paradigm in quantum crystallography by providing direct experimental access to wavefunction-derived properties in solids, with immediate applications in optoelectronic material design and fundamental studies of electron behavior in crystalline environments.