Roman Fanta, Ph.D. student Matúše Dubeckého obhájil svou disertační práci, gratulujeme!!!

Téma: Fixed-node diffusion Monte Carlo for noncovalent interactions.
Abstrakt: The omnipresence of noncovalent interactions in numerous physical, chemical, and biological phenomena necessitates accurate modeling of such interactions, which is not an easy task due to their complex quantum mechanical properties and the intricate interplay between different interaction types. The fixed-node diffusion Monte Carlo (FNDMC) many-body method has appeared as a potentially viable benchmarking method for large noncovalent and possibly periodic systems. This work seeks to enhance the precision and effectiveness of the single determinant (SD) FNDMC many-body method in the context of noncovalent periodic crystals and finite molecule systems. This undertaking involves a comprehensive exploration of relevant quantum-chemical methodologies, optimization of key technical parameters, and obtaining reference values of the lattice formation energy. The research underscores that while the FNDMC method has exhibited significant accuracy in calculations related to noncovalent interaction energies, its consistent benchmarking precision across diverse noncovalent interactions still needs to be proven. Thus, a comprehensive exploration of the SD FNDMC method’s capabilities and limitations in modeling noncovalent interactions is vital, which is the goal of this thesis. The ultimate ambition is to augment the application of SD FNDMC in noncovalent interactions, to enhance its reliability and maturity.