Pointillist rendering of electron charge and spin density suffices to replicate trends in atomic properties

Abstract

The monotonic and non-monotonic variations of atomic properties within and between the rows of the periodic table underlie our understanding of chemistry and accounting for these variations has been a signature strength of quantum mechanics (QM). However, the computational burden of QM motivates the development of more efficient means of describing electrons and reactivity. The recently developed LEWIS • model incorporates lessons learnt from QM into a force field that includes electrons as explicit pseudo-classical particles. Here, we extend LEWIS • across the 2p and 3p elements, and show that it is capable of reproducing both monotonic and non-monotonic variations of chemically important atomic properties in a cost-effective manner. An indicator of the strength of the construct is the ability of pairwise potentials trained on ionization energies and the order of spin configurations to predict atomic polarizabilities. In this manner, some insights of QM are uncoupled from its onerous computational burden.

Magnetism and Bond Order in Diatomic Molecules Described by Semiclassical Electrons

“…This construct is able to describe the aufbau, ionization energies, and polarizabilities of atoms of the reactive 2p and 3p elements. 13,14 Here we extend this approach to the spin states and bond orders of diatomic species at fixed bond length. In this regime, we discover an essential feature of the interparticle potentials that takes the construct one major and essential step closer to the ultimate goal of turn-key simulations of chemical reactions in systems with many degrees of freedom, for example, those in which solvent composition affects the rates and selectivities of chemical reactions.…”

Chemistry with semi-classical electrons: reaction trajectories auto-generated by sub-atomistic force fields

“…In our group, the first generation force field is LEWIS 4 , 5 and the second generation is LEWIS˙. 6 – 8 In the Caltech group the first generation force field is eFF 9 , 10 and the second generation is eFF–ECP 11 , 12 (where eFF stands for “electron force field” and ECP for “effective core potential”). Until well into these projects, neither of these groups was aware of the work of the other and the models from the two groups differ significantly.…”

Valence energy correction for electron reactive force field

“…Nevertheless, the procedures are limited to some range of elements and have not been used to describe complex reactions so far. [29][30][31][32] To treat electronelectron and nucleus-electron interactions in eFF, similar to eReaxFF, the methods use Gaussian wave packets to calculate the Coulomb point charge between the particles. However, eFF considered the Gaussian wave packet with a variable size of the electron's wave and includes Pauli repulsion, [32][33][34][35][36] while in eReaxFF electrons have a constant size.…”

“…The capability of both methods to calculate electronic affinities and to handle valence electrons are promising approaches. Nevertheless, the procedures are limited to some range of elements and have not been used to describe complex reactions so far 29–32 . To treat electron–electron and nucleus–electron interactions in eFF, similar to eReaxFF, the methods use Gaussian wave packets to calculate the Coulomb point charge between the particles.…”