Analytic nuclear forces and molecular properties from full configuration interaction quantum Monte Carlo

Thomas, Robert E.; Opalka, Daniel; Overy, Catherine; Knowles, Peter J.; Alavi, Ali; Booth, George H.

doi:10.1063/1.4927594

Cited by 30 publications

(34 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This error can be systematically reduced as the number of walkers is increased which enlarges the set of initiators. Other adaptations in recent years have also improved the accuracy and scope of the method, including the computation of excited states 54,55 , unbiased molecular properties [56][57][58] and its use as a solver within an active space framework 59,60 .…”

Section: A Fciqmc Methodsmentioning

confidence: 99%

Equation of state of atomic solid hydrogen by stochastic many-body wave function methods

Azadi,

Booth,

Kühne

2020

Preprint

Self Cite

View full text Add to dashboard Cite

We report a numerical study of the equation of state of crystalline body-centered-cubic (BCC) hydrogen, tackled with a variety of complementary many-body wave function methods. These include continuum stochastic techniques of fixed-node diffusion and variational quantum Monte Carlo, and the Hilbert space stochastic method of full configuration interaction quantum Monte Carlo. In addition, periodic coupled-cluster methods were also employed. Each of these methods is underpinned with different strengths and assumptions, but their combination in order to perform reliable extrapolation to complete basis set and supercell size limits gives confidence in the final results. The methods were found to be in good agreement for equilibrium cell volumes for the system in this phase, with a lattice parameter of 3.31 Bohr.

show abstract

Section: A Fciqmc Methodsmentioning

confidence: 99%

Equation of state of atomic solid hydrogen by stochastic many-body wave function methods

Azadi,

Booth,

Kühne

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The method still scales exponentially, but with a much reduced prefactor and has allowed FCI‐level calculations on much larger systems than attainable with conventional, deterministic algorithms . Within FCIQMC the one‐ and two‐body reduced density matrices can also be sampled, giving access to the evaluation of forces . Samanta et al have very recently showed how the approach can be extended to the calculation of dynamic linear response properties …”

Section: Reduced‐scaling: Alternative Approachesmentioning

confidence: 99%

Reduced‐scaling coupled cluster response theory: Challenges and opportunities

Crawford

Kumar

Bazanté

et al. 2019

WIREs Comput Mol Sci

View full text Add to dashboard Cite

We review the current state of reduced-scaling electron correlation methods, particularly coupled-cluster theory for the simulation and prediction of molecular response properties. The successes of local-coupled-cluster and related approaches are well known for reaction energies, thermodynamic constants, dipole moments, and so forth-properties that depend primarily on the quality of the ground-state wave function. However, much more challenging are higher-order properties such as polarizabilities, hyperpolarizabilities, optical rotations, magnetizabilities, and others that also require accurate representation of the derivative of the wave function to external electromagnetic fields. We discuss a range of methods for improving the correlation domains of such perturbed wave functions, including the use of "perturbation-aware" natural orbitals that are customized for the property of interest. In addition, we consider the viability and potential of promising, but stillemerging methods such as stochastic and real-time coupled-cluster approaches, for which the localizability of the field-dependent wave function may be more controllable than for conventional response theory.

show abstract

“…Crucially for our present purposes, the FCIQMC approach also facilitates the stochastically unbiased sampling of the two-body reduced density matrices (RDMs), 48,49 given by…”

Section: Methodsmentioning

confidence: 99%

“…The reduced density matrices allow for the calculation of a host of molecular properties including electrical moments, forces, and coupling to two-particle geminal functions, 48,49,53 but their chief use in this present study is in their access to the gradient, g, and Hessian, H, of the energy with respect to the orbital parameters,…”

Section: -52mentioning

confidence: 99%

Stochastic Multiconfigurational Self-Consistent Field Theory

Thomas

Sun

Alavi

et al. 2015

J. Chem. Theory Comput.

Self Cite

109

120

View full text Add to dashboard Cite

The multi-configurational self-consistent field theory is considered the standard starting point for almost all multireference approaches required for strongly-correlated molecular problems. The limitation of the approach is generally given by the number of strongly-correlated orbitals in the molecule, as its cost will grow exponentially with this number. We present a new multi-configurational self-consistent field approach, wherein linear determinant coefficients of a multi-configurational wavefunction are optimized via the stochastic full configuration interaction quantum Monte Carlo technique at greatly reduced computational cost, with nonlinear orbital rotation parameters updated variationally based on this sampled wavefunction. This extends this approach to strongly-correlated systems with far larger active spaces than it is possible to treat by conventional means. By comparison with this traditional approach, we demonstrate that the introduction of stochastic noise in both the determinant amplitudes and the gradient and Hessian of the orbital rotations does not preclude robust and reliable convergence of the orbital optimization. It can even improve the ability to avoid convergence to local minima in the orbital space, and therefore aid in finding variationally lower-energy solutions. We consider the effect on the convergence of the orbitals as the number of walkers and the sampling time within the active space increases, as well as the effect on the final energy and error. The scope of the new protocol is demonstrated with a study of the increasingly strongly correlated electronic structure in a series of polycyclic aromatic hydrocarbons, up to the large coronene molecule in a complete active space of 24 π electrons in 24 orbitals, requiring only modest computational resources.

show abstract

Analytic nuclear forces and molecular properties from full configuration interaction quantum Monte Carlo

Cited by 30 publications

References 72 publications

Equation of state of atomic solid hydrogen by stochastic many-body wave function methods

Equation of state of atomic solid hydrogen by stochastic many-body wave function methods

Reduced‐scaling coupled cluster response theory: Challenges and opportunities

Stochastic Multiconfigurational Self-Consistent Field Theory

Contact Info

Product

Resources

About