Jacques K. Desmarais

Sep 25, 2024 | link.aps.org | Jacques K. Desmarais |Dipartimento di Chimica |Università di Torino |Giovanni Vignale

Understanding of bonding is key to modeling materials and predicting properties thereof. A widely adopted indicator of bonds and atomic shells is the electron localization function (ELF). The building blocks of the ELF are also used in the construction of modern density functional approximations. Here, we demonstrate that the ELF breaks down when applied beyond regular nonrelativistic quantum states.

Jun 21, 2024 | link.aps.org | Jacques K. Desmarais |Dipartimento di Chimica |Università di Torino |Jefferson Maul

The prominence of density functional theory in the field of electronic structure computation stems from its ability to usefully balance accuracy and computational effort. At the base of this ability is a functional of the electron density: the exchange-correlation energy. This functional satisfies known exact conditions that guide the derivation of approximations. The strongly constrained and appropriately normed (SCAN) approximation stands out as a successful, modern, example.

Oct 16, 2023 | link.aps.org | Jacques K. Desmarais |Dipartimento di Chimica |Università di Torino |Alessandro Erba

Analytical gradients of the total energy are worked out for local density, generalized-gradient, and hybrid approximations to generalized Kohn-Sham spin-current density functional theory (SCDFT) of materials. It is shown that gradients can be determined analytically, in a two-component framework, including spin-orbit coupling (SOC), with high accuracy.

Jun 28, 2023 | link.aps.org | Jacques K. Desmarais |Dipartimento di Chimica |Università di Torino |Bernard Kirtman

Abstract An analysis of orbital magnetization in insulators is provided. It is shown that a previously proposed electronic orbital angular-momentum operator generalizes the “modern theory of orbital magnetization” to include nonlocal Hamiltonians. Expressions for magnetic transition dipole moments needed for the calculation of optical rotation and other properties are developed. A variety of issues that arise in this context are critically analyzed.