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Neural Networks vs Gaussian Process Regression for Representing Potential Energy Surfaces: a Comparative Study of Fit Quality and Vibrational Spectrum Accuracy
(2018)
For molecules with more than three atoms, it is difficult to fit or interpolate a potential energy surface (PES) from a small number of (usually ab initio) energies at points. Many methods have been proposed in recent ...
Using Monomer Vibrational Wavefunctions to Compute Numerically Exact (12D) Rovibrational Levels of Water Dimer
(2017)
We compute numerically exact rovibrational levels of water dimer, with 12 vibrational coordinates, on the accurate CCpol-8sf ab initio flexible monomer potential energy surface[J. Chem. Phys. 137, 014305 (2012)]. It does ...
Full-Dimensional Calculations of Rovibrational Levels of Five-Atom Molecules Using Two Different Strategies: Applications to CH4, CHD3, CH3D and CH3F
(2018)
Quantum mechanical calculations of ro-vibrational energies of CH4, CHD3, CH3D, and CH3F were made with two different numerical approaches. Both use polyspherical coordinates. The computed energy levels agree, confirming the ...
Using an Iterative Eigensolver and Intertwined Rank Reduction to Compute Vibrational Spectra of Molecules With More Than a Dozen Atoms: Uracil and Naphthalene
(2017-02-10)
We use a direct product basis, basis vectors computed by evaluating matrix-vector products, and rank reduction to calculate vibrational energy levels of uracil and naphthalene, with 12 and 18 atoms, respectively. A matrix ...
Redundant Coordinates in Quantum Mechanics
(2018)
We present a kinetic energy operator and inner product that can be used to solve the Schroedinger equation in redundant coordinates. The goal is to develop equations and a computational procedure that can be used with N ...
Ab Initio Study of the CO–N2 Complex: a New Highly Accurate Intermolecular Potential Energy Surface and Rovibrational Spectrum
(2018-03-01)
A new, highly accurate ab initio ground-state intermolecular potential-energy surface (IPES) for the CO-N2 complex is presented. Thousands of interaction energies calculated with the CCSD(T) method and Dunning’s aug-cc-pVQZ ...
A New Collocation-Based Multi-Configuration Time-Dependent Hartree (MCTDH) Approach for Solving the Schrödinger Equation With a General Potential Energy Surface
(2018-01-08)
We present a new collocation-based multi-configuration time-dependent Hartree (MCTDH) approach for solving the Schrödinger equation required to compute (ro-)vibrational spectra, photodissociation cross sections, reaction ...
Computing Vibration–Rotation-Tunnelling Levels of HOD Dimer
(2017)
Using an accurate 6D water dimer potential energy surface, we compute vibration-rotation tunnelling levels of HOD dimer, by assuming that the two monomers are rigid. HOD dimer has two isomers, a D-bonded isomer and an ...
Iterative Methods for Computing Vibrational Spectra
(2017-12-21)
I review some computational methods for calculating vibrational spectra. They all use iterative eigensolvers to compute eigenvalues of a Hamiltonian matrix by evaluating matrix-vector products. A direct-product basis can ...