Communication: Variation after response in quantum Monte Carlo

Neuscamman, Eric

doi:10.1063/1.4961686

Cited by 17 publications

(35 citation statements)

References 36 publications

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“…The previous studies through using the single‐ and multideterminant trial wave functions show that the QMC methods could provide an accurate description for both the ground and excited state properties . However, these studies have revealed that there is a strong dependence between the accuracy of the obtained energies and the quality of the trial wave function in the ground and excited states.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Monte Carlo study of ground and first excited state of C, N, O, F, and Ne atoms using Slater‐Jastrow‐Backflow wave function

Nasiri

Zahedi

2020

Int J of Quantum Chemistry

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All-electron fixed-node diffusion quantum Monte Carlo energies of the two lowestlying states of C, N, O, F, and Ne atoms are reported. The Slater-Jastrow form is used as the trial wave function. We will use single-and multideterminant wave functions as the Slater part. The single-determinant wave function has been computed by the Hartree-Fock method and the multideterminant wave functions have been computed by the complete active space self-consistent field, configuration interaction with single and double excitation, configuration interaction with single, double, triple, and quadruple excitation and second-order configuration interaction. For the groundand first excited states, the multideterminant wave functions have computed more than 99% of the correlation energy. Significant improvements have been achieved using the backflow transformations and up to 99.8% of the correlation energy has been recovered. A very good agreement with the experimental data has been obtained for the excitation energies. K E Y W O R D S backflow transformation, excited state, ground state of C, N, O an F atoms, quantum montecarlo, Slater-Jastrow

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Section: Introductionmentioning

confidence: 99%

“…). Additionally, Eric Neuscamman proposed “Variation after response “method [9] in which it was claimed that the obtained results are more accurate than those of the former one.…”

Section: Introductionmentioning

confidence: 99%

Quantum Monte Carlo study of ground and first excited state of C, N, O, F, and Ne atoms using Slater‐Jastrow‐Backflow wave function

Nasiri

Zahedi

2020

Int J of Quantum Chemistry

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“…We recently introduced an ansatz that we call the finite-difference linear response (FDLR) wave function 16,17 . The FDLR approach allows one to consider a general wave function, and to construct a significantly more flexible ansatz in its linear response space.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Diffusion Monte Carlo Calculations: A Simple and Efficient Two-Determinant Ansatz

Blunt¹,

Neuscamman

2018

J. Chem. Theory Comput.

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We perform excited-state variational Monte Carlo and diffusion Monte Carlo calculations using a simple and efficient wave function ansatz. This ansatz follows the recent variation-after-response formalism, accurately approximating a configuration interaction singles wave function as a sum of only two non-orthogonal Slater determinants, and further including important orbital relaxation. The ansatz is used to perform diffusion Monte Carlo calculations with large augmented basis sets, comparing to benchmarks from near-exact quantum chemical methods. The significance of orbital optimization in excited-state diffusion Monte Carlo is demonstrated, and the excited-state optimization procedure is discussed in detail. Diffuse excited states in water and formaldehyde are studied, in addition to the formaldimine and benzonitrile molecules. arXiv:1808.09549v2 [cond-mat.str-el]

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“…This ansatz follows the recently-introduced variation-afterresponse (VAR) approach. 33 Specifically, we consider the linear response space of an optimizable determinant, which contains the full flexibility of a configuration interaction singles (CIS) wave function, 34 together with orbital rotations. Using a finite-difference approximation, this wave function may be expressed efficiently as a difference of two Slater-Jastrow functions.…”

Section: Introductionmentioning

confidence: 99%

Charge-transfer excited states: Seeking a balanced and efficient wave function ansatz in variational Monte Carlo

Blunt

Neuscamman

2017

The Journal of Chemical Physics

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We present a simple and efficient wave function ansatz for the treatment of excited charge-transfer states in real-space quantum Monte Carlo methods. Using the recently introduced variation-after-response method [E. Neuscamman, J. Chem. Phys. 145, 081103 (2016)], this ansatz allows a crucial orbital optimization step to be performed beyond a configuration interaction singles expansion, while only requiring calculation of two Slater determinant objects. We demonstrate this ansatz for the illustrative example of the stretched LiF molecule, for a range of excited states of formaldehyde, and finally for the more challenging ethylene-tetrafluoroethylene molecule.

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Communication: Variation after response in quantum Monte Carlo

Cited by 17 publications

References 36 publications

Quantum Monte Carlo study of ground and first excited state of C, N, O, F, and Ne atoms using Slater‐Jastrow‐Backflow wave function

Quantum Monte Carlo study of ground and first excited state of C, N, O, F, and Ne atoms using Slater‐Jastrow‐Backflow wave function

Excited-State Diffusion Monte Carlo Calculations: A Simple and Efficient Two-Determinant Ansatz

Charge-transfer excited states: Seeking a balanced and efficient wave function ansatz in variational Monte Carlo

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