238 citations · 627 across the 19 of their papers we have counts for
20 papers
CIS(2): a state-specific, size-intensive perturbative correction to configuration interaction singles
Takashi Tsuchimochi
We present a state-specific second-order perturbation theory based on a configuration interaction singles (CIS) reference and its generalized Fock operator. Starting from a fully i…
Analytical Nuclear Gradients for State-Averaged Configuration Interaction Singles Variants: Application to Conical Intersections
Takashi Tsuchimochi
We derive analytical nuclear gradients for state-averaged orbital-optimized configuration interaction singles (SACIS) and its spin-projected extension (SAECIS), enabling efficient…
Classically Driven Hybrid Quantum Algorithms with Sequential Givens Rotations for Reduced Measurement Cost
Benjamin Mokhtar, Noboru Inoue, Takashi Tsuchimochi
Quantum algorithms for electronic-structure simulations are actively being developed, yet many hybrid quantum-classical approaches are bottlenecked by the measurement overhead asso…
TDSCF: Time-Dependent Density Functional Theory with a Non-Aufbau Reference for near-degenerate states
Shuto Shibasaki, Fumiya Mohri, Takashi Tsuchimochi
Near-degenerate electronic structures remain a major challenge for conventional single-reference density functional theory (DFT). To address this problem, we propose time-dependent…
Leveraging configuration interaction singles for qualitative descriptions of ground and excited states: state-averaging, linear-response, and spin-projection
Takashi Tsuchimochi, Benjamin Mokhtar
While configuration interaction singles (CIS) provides a computationally efficient description of excited states, it systematically overestimates excitation energies and performs p…
Double Configuration Interaction Singles: Scalable and size-intensive approach for orbital relaxation in excited states and bond-dissociation
Takashi Tsuchimochi
We present a novel theoretical scheme for orbital relaxation in configuration interaction singles (CIS) based on a perturbative treatment of its electronic Hessian, whose analytica…
Many-Body-Expansion Based on Variational Quantum Eigensolver and Deflation for Dynamical Correlation
Enhua Xu, Yuma Shimomoto, Seiichiro L. Ten-no +1
In this study, we utilize the many-body expansion (MBE) framework to decompose electronic structures into fragments by incrementing the virtual orbitals. Our work aims to accuratel…
Improved algorithms of quantum imaginary time evolution for ground and excited states of molecular systems
Takashi Tsuchimochi, Yoohee Ryo, Seiichiro L. Ten-no
Quantum imaginary time evolution (QITE) is a recently proposed quantum-classical hybrid algorithm that is guaranteed to reach the lowest state of system. In this study, we present…
Multi-state quantum simulations via model-space quantum imaginary time evolution
Takashi Tsuchimochi, Yoohee Ryo, Siu Chung Tsang +1
We introduce the framework of model space into quantum imaginary time evolution (QITE) to enable stable estimation of ground and excited states using a quantum computer. Model-spac…
Adaptive construction of shallower quantum circuits with quantum spin projection for fermionic systems
Takashi Tsuchimochi, Masaki Taii, Taisei Nishimaki +1
Quantum computing is a promising approach to harnessing strong correlation in molecular systems; however, current devices only allow for hybrid quantum-classical algorithms with a…
Spin-projection for quantum computation: A low-depth approach to strong correlation
Takashi Tsuchimochi, Yuto Mori, Seiichiro L. Ten-no
Although spin is a core property in fermionic systems, its symmetry can be easily violated in a variational simulation, especially when strong correlation plays a vital role therei…
Second-order perturbation theory with spin-symmetry projected Hartree-Fock
Takashi Tsuchimochi, Seiichiro L. Ten-no
We propose two different schemes for second-order perturbation theory with spin-projected Hartree-Fock. Both schemes employ the same ansatz for the first-order wave function, which…
Bridging single- and multireference domains for electron correlation: spin-extended coupled electron pair approximation
Takashi Tsuchimochi, Seiichiro Ten-no
We propose a size-consistent generalization of the recently developed spin-extended configuration interaction with singles and doubles (ECISD), where a CI wave function is explicit…
General technique for analytical derivatives of post-projected Hartree-Fock
Takashi Tsuchimochi, Seiichiro Ten-no
In electronic structure theory, the availability of analytical derivative is one of the desired features for a method to be useful in practical applications, as it allows for geome…
Configuration interaction combined with spin-projection for strongly correlated molecular electronic structures
Takashi Tsuchimochi, Seiichiro Ten-no
We introduce single and double particle-hole excitations in the recently revived spin-projected Hartree-Fock. Our motivation is to treat static correlation with spin-projection and…
Extended Møller-Plesset perturbation theory for dynamical and static correlations
Takashi Tsuchimochi, Troy Van Voorhis
We present a novel method that appropriately handles both dynamical and static electron correlation in a balanced manner, using a perturbation theory on a spin-extended Hartree-Foc…
Projected Hartree-Fock Theory
Carlos A. Jimenez-Hoyos, Thomas M. Henderson, Takashi Tsuchimochi +1
Projected Hartree-Fock theory (PHF) has a long history in quantum chemistry. PHF is here understood as the variational determination of an N-electron broken symmetry Slater determi…
ROHF Theory Made Simple
Takashi Tsuchimochi, Gustavo E. Scuseria
Restricted open-shell Hartree-Fock (ROHF) theory is formulated as a projected self-consistent unrestricted HF (UHF) model by mathematically constraining spin density eigenvalues. T…
Constrained-Pairing Mean-Field Theory. IV. Inclusion of corresponding pair constraints and connection to unrestricted Hartree-Fock theory
Takashi Tsuchimochi, Thomas M. Henderson, Gustavo E. Scuseria +1
Our previously developed Constrained-Pairing Mean-Field Theory (CPMFT) is shown to map onto an Unrestricted Hartree-Fock (UHF) type method if one imposes a corresponding pair const…
Strong correlations via constrained-pairing mean-field theory
Takashi Tsuchimochi, Gustavo E. Scuseria
We present a mean-field approach for accurately describing strong correlations via electron number fluctuations and pairings constrained to an active space. Electron number conserv…