Automated construction of potential energy surfaces

State‐to‐state photodissociation dynamics of the water molecule

“…However, accurate characterization of these processes is a very challenging endeavor. While the quantum mechanical formulation for simulating photodissociation dynamics has been established sometimes ago, accurate coupled diabatic potential energy surfaces (PESs) were rarely available until recently, thanks to rapid advances in ab initio theory and fitting approaches that have made PESs and nonadiabatic couplings of polyatomic systems more reliable than before . Despite extensive studies on photodissociation dynamics in polyatomic molecules, quantitative agreements with experiments have just started to emerge for polyatomic systems dominated by nonadiabatic transitions .…”

A critical comparison of neural network potentials for molecular reaction dynamics with exact permutation symmetry

“…Therefore, developing accurate PESs is of great significance in the field of theoretical/computational chemistry. While the accuracy of empirical potentials relying on physical approximations is often limited, numerous approaches have been developed to represent PESs based on very flexible and purely mathematical functional forms, which can be grouped into two categories: (1) interpolation methods, which provide error-free energies for the available reference data but interpolate in between, such as cubic splines, reproducing kernel Hilbert space (RKHS), 1 interpolating moving least square (IMLS) 2 and modified Shepard interpolation (MSI) methods; 3 and (2) fitting methods relying on specific functional forms such as polynomials within the many body expansion regime, 4,5 sum-of-product forms 6,7 and permutation invariant polynomials (PIPs). [8][9][10] In spite of all these methods, the accurate description of global PESs has remained a formidable challenge even for comparably small polyatomic systems, because they often exhibit a complex topology with several reactants and products, saddle points and intermediates, and in general it is impossible to derive suitable functional forms based on physical considerations.…”

Computational study of the rovibrational spectrum of (CO2)2

“…It is also possible to use inter-atomic coordinates and permutation invariant functions. [47,48] (12) and (34) are not on the stored portion of the grid. (12) affects the vibrational angles as follows, (12)…”