Casimir Self-Interaction Energy Density of Quantum Electrodynamic Fields

in Physical Review Letters (2023)

Quantum machine learning corrects classical forcefields: Stretching DNA base pairs in explicit solvent

in Journal of Chemical Physics (2022), 157(6),

In order to improve the accuracy of molecular dynamics simulations, classical forcefields are supplemented with a kernel-based machine learning method trained on quantum-mechanical fragment energies. As ... [more ▼]

In order to improve the accuracy of molecular dynamics simulations, classical forcefields are supplemented with a kernel-based machine learning method trained on quantum-mechanical fragment energies. As an example application, a potential-energy surface is generalized for a small DNA duplex, taking into account explicit solvation and long-range electron exchange–correlation effects. A long-standing problem in molecular science is that experimental studies of the structural and thermodynamic behavior of DNA under tension are not well confirmed by simulation; study of the potential energy vs extension taking into account a novel correction shows that leading classical DNA models have excessive stiffness with respect to stretching. This discrepancy is found to be common across multiple forcefields. The quantum correction is in qualitative agreement with the experimental thermodynamics for larger DNA double helices, providing a candidate explanation for the general and long-standing discrepancy between single molecule stretching experiments and classical calculations of DNA stretching. The new dataset of quantum calculations should facilitate multiple types of nucleic acid simulation, and the associated Kernel Modified Molecular Dynamics method (KMMD) is applicable to biomolecular simulations in general. KMMD is made available as part of the AMBER22 simulation software. [less ▲]

BIGDML—Towards accurate quantum machine learning force fields for materials

in Nature Communications (2022)

Colossal Enhancement of Atomic Force Response in van der Waals Materials Arising from Many-Body Electronic Correlations

in Physical Review Letters (2022)

Molecular Interactions Induced by a Static Electric Field in Quantum Mechanics and Quantum Electrodynamics

in Journal of Physical Chemistry Letters (2022)

Dimensionality reduction in machine learning for nonadiabatic molecular dynamics: Effectiveness of elemental sublattices in lead halide perovskites

in Journal of Chemical Physics (2022)

Interpolating Nonadiabatic Molecular Dynamics Hamiltonian with Artificial Neural Networks

in Journal of Physical Chemistry Letters (2022)

The three-center two-positron bond

in Chemical Science (2022)

Computational studies have shown that one or more positrons can stabilize two repelling atomic anions through the formation of two-center positronic bonds. In the present work, we study the energetic ... [more ▼]

Computational studies have shown that one or more positrons can stabilize two repelling atomic anions through the formation of two-center positronic bonds. In the present work, we study the energetic stability of a system containing two positrons and three hydride anions, namely 2e+[H3-3]. To this aim, we performed a preliminary scan of the potential energy surface of the system with both electrons and positron in a spin singlet state, with a multi-component MP2 method, that was further refined with variational and diffusion Monte Carlo calculations, and confirmed an equilibrium geometry with D3h symmetry. The local stability of 2e+[H3-3] is demonstrated by analyzing the vertical detachment and adiabatic energy dissociation channels. Bonding properties of the positronic compound, such as the equilibrium interatomic distances, force constants, dissociation energies, and bonding densities are compared with those of the purely electronic H+3 and Li+3 systems. Through this analysis, we find compelling similarities between the 2e+[H3-3] compound and the trilithium cation. Our results strongly point out the formation of a non-electronic three-center two-positron bond, analogous to the well-known three-center two-electron counterparts, which is fundamentally distinct from the two-center two-positron bond [D. Bressanini, J. Chem. Phys.155, 054306 (2021)], thus extending the concept of positron bonded molecules. [less ▲]

Anisotropic Interlayer Force Field for Transition Metal Dichalcogenides: The Case of Molybdenum Disulfide

in Journal of Chemical Theory and Computation (2021)

Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package

in Journal of Chemical Physics (2021)