## Search

Now showing items 1-10 of 32

#### Machine learning optimization of the collocation point set for solving the electronic Schrödinger equation

(2019)

The rectangular collocation approach makes it possible to solve the Schrödinger equation with basis functions that do not have amplitude in all regions in which wavefunctions have significant amplitude. Collocation points ...

#### Perspective: Computing (ro-)Vibrational Spectra of Molecules With More Than Four Atoms

(2017-03-31)

In this perspective, I review methods for computing (ro-)vibrational energy levels and wavefunctions of molecules with more than four atoms. I identify three problems one confronts (1) reducing the size of the basis; (2) ...

#### An Intertwined Method for Making Low-Rank, Sum-Of-Product Basis Functions that makes it Possible to Compute Vibrational Spectra of Molecules with more than 10 Atoms

(2017-05-31)

We propose a method for solving the vibrational Schrödinger equation with which one can compute spectra for molecules with more than ten atoms. It uses sum-of-product (SOP) basis functions stored in a canonical polyadic ...

#### Systematically Expanding Nondirect Product Bases Within the Pruned Multi-Configuration ime-dependent Hartree (MCTDH) Method: A Comparison With Multi-Layer MCTDH

(2017-05-21)

We propose a pruned multi-configuration time-dependent Hartree (MCTDH) method with systematically expanding nondirect product bases and use it to solve the time-independent Schrödinger equation. No pre-determined pruning ...

#### 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 ...

#### Using Monomer Vibrational Wavefunctions as Contracted Basis Functions to Compute Rovibrational Levels of an H2O-Atom Complex in Full Dimensionality

(2017-03-31)

In this paper, we present new ideas for computing rovibrational energy levels of molecules composed of two components and apply them to H2O–Cl−. When both components are themselves molecules, Euler angles that specify their ...

#### 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 Rectangular Collocation with Finite Difference Derivatives to Solve Electronic Schrödinger Equation

(2018)

We show that a rectangular collocation method, equivalent to evaluating all matrix elements with a quadrature-like scheme and using more points than basis functions, is an effective approach for solving the electronic ...

#### 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 ...

#### 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 ...