Excited-state downfolding using ground-state formalisms DOI Creative Commons
Nicholas P. Bauman

Electronic Structure, Год журнала: 2024, Номер 6(2), С. 025003 - 025003

Опубликована: Май 2, 2024

Abstract Downfolding coupled cluster (CC) techniques are powerful tools for reducing the dimensionality of many-body quantum problems. This work investigates how ground-state downfolding formalisms can target excited states using non-Aufbau reference determinants, paving way applications computing in excited-state chemistry. study focuses on doubly which canonical equation-of-motion CC approaches struggle to describe unless one includes higher-than-double excitations. The technique results state-specific effective Hamiltonians that, when diagonalized their respective active spaces, provide ground- and total energies (and therefore excitation energies) comparable high-level methods. performance this procedure is examined with H 2 , Methylene, Formaldehyde, Nitroxyl.

Язык: Английский

Quantum Computed Green's Functions using a Cumulant Expansion of the Lanczos Method DOI Creative Commons
Gabriel Greene‐Diniz, David Zsolt Manrique, Kentaro Yamamoto

и другие.

Quantum, Год журнала: 2024, Номер 8, С. 1383 - 1383

Опубликована: Июнь 20, 2024

In this paper, we present a quantum computational method to calculate the many-body Green's function matrix in spin orbital basis. We apply our approach finite-sized fermionic Hubbard models and related impurity within Dynamical Mean Field Theory, demonstrate calculation of functions on Quantinuum's H1-1 trapped-ion computer. Our involves cumulant expansion Lanczos method, using Hamiltonian moments as measurable expectation values. This bypasses need for large overhead number measurements due repeated applications variational eigensolver (VQE), instead measures value with one set measurement circuits. From measured moments, tridiagonalised can be computed, which turn yields via continued fractions. While use algorithm prepare ground state work, note that modularity implementation allows other (non-variational) approaches used state.

Язык: Английский

Процитировано

3
Generalized Spin in the Variance-Based Wave Function Optimization Method within the Doubly Occupied Configuration Interaction Framework DOI
Diego R. Alcoba, Luís Laín, Alicia Torre

и другие.

The Journal of Physical Chemistry A, Год журнала: 2024, Номер 128(34), С. 7277 - 7283

Опубликована: Авг. 14, 2024

In this work, we implement a generalized spin formulation of the doubly occupied configuration interaction methodology using energy variance N-electron Hamiltonian. We perform optimization wave functions and calculate their corresponding energies, unified variational treatment for ground excited states based on variance, which allows us to describe entire spectra an equal footing. analyze effects produced by breakdown Ŝ2 Ŝz symmetries in model hydrogenic clusters terms energies spin-related quantities, arising from restricted, unrestricted, methods. The results are compared with other related methods as well full interaction.

Язык: Английский

Процитировано

3
Energy Landscapes for the Unitary Coupled Cluster Ansatz DOI Creative Commons
Choy Boy, Maria-Andreea Filip, David J. Wales

и другие.

Journal of Chemical Theory and Computation, Год журнала: 2025, Номер unknown

Опубликована: Фев. 16, 2025

The unitary coupled cluster (UCC) approach has been one of the most popular wavefunction parametrizations for variational quantum eigensolver due to relative ease optimization compared hardware-efficient ansätze. In this contribution, we explore energy landscape singles and doubles (UCCSD) two commonly employed benchmark systems, lithium hydride nitrogen dimer. We investigate organization solution space in terms local minima show how it changes as number order operators UCC ansatz are varied. Surprisingly, find that all cases, UCCSD numerous low-lying connected by high transition states. Additionally, spread lie same band global minimum may exceed chemical accuracy, making location true especially challenging.

Язык: Английский

Процитировано

0
Quantum computing for molecular vibrational energies: A comprehensive study DOI Creative Commons

R. Somasundaram,

R Jayaharish,

Rohith Ramanan

и другие.

Deleted Journal, Год журнала: 2025, Номер unknown, С. 100031 - 100031

Опубликована: Апрель 1, 2025

Язык: Английский

Процитировано

0
Fighting Noise with Noise: A Stochastic Projective Quantum Eigensolver DOI Creative Commons
Maria-Andreea Filip

Journal of Chemical Theory and Computation, Год журнала: 2024, Номер 20(14), С. 5964 - 5981

Опубликована: Июль 2, 2024

In the current noisy intermediate scale quantum era of computation, available hardware is severely limited by both qubit count and noise levels, precluding application many hybrid quantum-classical algorithms to nontrivial chemistry problems. this paper we propose applying some fundamental ideas conventional Quantum Monte Carlo algorithms─stochastic sampling wave function Hamiltonian─to in order significantly decrease resource costs. context an imaginary-time propagation based projective eigensolver, present a novel approach estimating physical observables which can lead magnitude reduction required state converge ground energy system relative state-of-the-art eigensolvers. The method be equally applied excited-state calculations and, combined with stochastic approximations Hamiltonian, provides promising near-term Hamiltonian simulation for general on devices.

Язык: Английский

Процитировано

2
Subspace-Search Quantum Imaginary Time Evolution for Excited State Computations DOI
Cameron Cianci, Lea F. Santos, Víctor S. Batista

и другие.

Journal of Chemical Theory and Computation, Год журнала: 2024, Номер 20(20), С. 8940 - 8947

Опубликована: Окт. 1, 2024

Quantum systems in excited states are attracting significant interest with the advent of noisy intermediate-scale quantum (NISQ) devices. While ground small molecular typically explored using hybrid variational algorithms like eigensolver (VQE), study has received much less attention, partly due to absence efficient algorithms. In this work, we introduce

Язык: Английский

Процитировано

1
Quantum Computed Green's Functions using a Cumulant Expansion of the Lanczos Method DOI Creative Commons
Gabriel Greene‐Diniz, David Zsolt Manrique, Kentaro Yamamoto

и другие.

arXiv (Cornell University), Год журнала: 2023, Номер unknown

Опубликована: Янв. 1, 2023

In this paper, we present a quantum computational method to calculate the many-body Green's function matrix in spin orbital basis. We apply our approach finite-sized fermionic Hubbard models and related impurity within Dynamical Mean Field Theory, demonstrate calculation of functions on Quantinuum's H1-1 trapped-ion computer. Our involves cumulant expansion Lanczos method, using Hamiltonian moments as measurable expectation values. This bypasses need for large overhead number measurements due repeated applications variational eigensolver (VQE), instead measures value with one set measurement circuits. From measured moments, tridiagonalised can be computed, which turn yields via continued fractions. While use algorithm prepare ground state work, note that modularity implementation allows other (non-variational) approaches used state.

Язык: Английский

Процитировано

1
Excited-state downfolding using ground-state formalisms DOI Creative Commons
Nicholas P. Bauman

Electronic Structure, Год журнала: 2024, Номер 6(2), С. 025003 - 025003

Опубликована: Май 2, 2024

Abstract Downfolding coupled cluster (CC) techniques are powerful tools for reducing the dimensionality of many-body quantum problems. This work investigates how ground-state downfolding formalisms can target excited states using non-Aufbau reference determinants, paving way applications computing in excited-state chemistry. study focuses on doubly which canonical equation-of-motion CC approaches struggle to describe unless one includes higher-than-double excitations. The technique results state-specific effective Hamiltonians that, when diagonalized their respective active spaces, provide ground- and total energies (and therefore excitation energies) comparable high-level methods. performance this procedure is examined with H 2 , Methylene, Formaldehyde, Nitroxyl.

Язык: Английский

Процитировано

0