Article
Chemistry, Multidisciplinary
Hector H. Corzo, Andreas Erbs Hillers-Bendtsen, Ashleigh Barnes, Abdulrahman Y. Zamani, Filip Pawlowski, Jeppe Olsen, Poul Jorgensen, Kurt V. Mikkelsen, Dmytro Bykov
Summary: This study addresses the computational challenges of investigating complex chemical systems using ab-initio methodologies. The researchers introduce the Divide-Expand-Consolidate (DEC) approach, which is a linear-scaling, massively parallel framework, as a viable solution for coupled cluster (CC) theory. They also present the cluster perturbation theory to mitigate the inherent limitations of DEC. Furthermore, they propose the CPS (D-3) model, derived from a CC singles parent and a doubles auxiliary excitation space, for efficient computation of excitation energies in large molecular systems. Overall, this study provides new algorithms and frameworks that can significantly improve the calculation of molecular properties.
FRONTIERS IN CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Junzi Liu, Lan Cheng
Summary: The article reviews the development of relativistic coupled-cluster and equation-of-motion coupled-cluster methods, focusing on recent efforts to improve computational efficiency and extend the methods to molecules containing heavy elements. Future directions for the development of these methods are also discussed.
WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE
(2021)
Article
Chemistry, Physical
Robin Feldmann, Alberto Baiardi, Markus Reiher
Summary: We propose a symmetry projection technique for enforcing rotational and parity symmetries in nuclear-electronic Hartree-Fock wave functions, which treats electrons and nuclei equally. By projecting the wave function onto representations of the three-dimensional rotation group, the technique generates a trial wave function with the correct symmetry properties and makes the wave function an eigenfunction of the angular momentum operator.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Physical
Robin Feldmann, Alberto Baiardi, Markus Reiher
Summary: In this paper, a symmetry projection technique is presented for enforcing rotational and parity symmetries in nuclear-electronic Hartree-Fock wave functions. A trial wave function with the correct symmetry properties is generated by projecting the wave function onto representations of the three-dimensional rotation group. The efficiency of the technique is demonstrated by calculating the energies of low-lying rotational states of H-2 and H-3(+) molecules.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Review
Chemistry, Multidisciplinary
Benedicte Sverdrup Ofstad, Einar Aurbakken, Oyvind Sigmundson Schoyen, Hakon Emil Kristiansen, Simen Kvaal, Thomas Bondo Pedersen
Summary: In recent years, there has been growing interest in time-dependent coupled-cluster (TDCC) theory for simulating laser-driven electronic dynamics in atoms and molecules, as well as molecular vibrational dynamics. This review covers different types of single-reference TDCC theory based on orthonormal static, orthonormal time-dependent, or biorthonormal time-dependent spin orbitals. The time-dependent extension of equation-of-motion coupled-cluster theory and various applications of TDCC methods are also discussed, including the calculation of linear absorption spectra, response functions, high harmonic generation spectra, and ionization dynamics. Additionally, the role of TDCC theory in finite-temperature many-body quantum mechanics and other application areas is briefly described.
WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE
(2023)
Article
Chemistry, Physical
Tobias Schafer, Florian Libisch, Georg Kresse, Andreas Gruneis
Summary: An embedding approach is presented to efficiently handle local electron correlation effects in periodic environments by integrating high-level correlation calculations into low-level ones. The method demonstrates accelerated convergence with respect to the local fragment size and has shown capabilities in accurately calculating adsorption energies of molecules and lattice impurities in solids.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Niels Kristian Madsen, Rasmus Berg Jensen, Ove Christiansen
Summary: The first implementation of tensor-decomposed vibrational coupled cluster response theory for calculating vibrational excitation energies is presented in this study, where the CP-VCC algorithm has been generalized to allow transformations with the Jacobian matrix and a new eigenvalue solver is introduced. Numerical results show that errors introduced by tensor decomposition can be controlled by numerical thresholds, and the approach allows for black-box calculations with minimal user input. Efficient computation of eigenstates of PAHs without explicitly constructed tensors is also demonstrated, improving memory and CPU time compared to full-tensor versions.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Jia Chen, Hai-Ping Cheng, James K. Freericks
Summary: The factorized form of UCC shows similar accuracy to conventional CC for weakly correlated molecules and significantly outperforms CI for strongly correlated molecules, making it an accurate, efficient, and reliable electronic structure method in both weakly and strongly correlated regions. This classical algorithm allows for robust benchmarking of anticipated quantum computing results and application of coupled-cluster techniques to more strongly correlated molecules.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Ruiheng Song, Thomas M. Henderson, Gustavo E. Scuseria
Summary: The study presents an alternative approach to address the connection between weakly correlated and strongly correlated systems, and shows promising results.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Mushir Thodika, Spiridoula Matsika
Summary: This article discusses the formation of anion resonances in low-energy electron-induced reactions and proposes a new method for characterizing these resonances. By introducing a projected complex absorbing potential within the multireference configuration interaction framework, the authors are able to efficiently capture the mixing between different channels, showing significant consequences for the resonances' lifetimes.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Daniil A. Fedotov, Sonia Coriani, Christof Haettig
Summary: The study presents an implementation of a complex solver for computing the complex response functions of damped response theory. The solver uses a partitioned formulation to avoid storing double excitation amplitudes, making it widely applicable in the context of the resolution-of-identity (RI) coupled cluster singles and approximate doubles (CC2) method.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Ecology
Simon Scheiter, Dushyant Kumar, Mirjam Pfeiffer, Liam Langan
Summary: This study aimed to assess how different biome classification schemes influence current and projected future biome patterns. The results showed that the choice of classification scheme strongly influenced the resulting biome patterns, but consistently demonstrated that grassland and savanna areas are most susceptible to climate change, while tropical forests and deserts are relatively stable.
GLOBAL ECOLOGY AND BIOGEOGRAPHY
(2023)
Article
Spectroscopy
Yi-Wei Fan, Huai-Qian Wang, Hui-Fang Li
Summary: The study on hydrated clusters Co(H2O)(n)(-) in gas phase using DFT coupled with stochastic kicking method reveals that the global minimum structure of Co(H2O)(n)(-) exhibits a low-symmetry pattern. The Co- ion tends to be located at the vertex site of the water molecular clusters to reduce repulsion with O atom. These results demonstrate that the formation of these low-lying isomers is determined by the delicate balance between ion-water and water-water interactions.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2021)
Article
Chemistry, Physical
A. Eugene DePrince
Summary: The study utilizes Quantum Electrodynamics Coupled-Cluster (QED-CC) theory to model the changes in ground-state properties of a series of sodium halide compounds strongly coupled to an optical cavity. It shows that electron affinities (EAs) are significantly affected by cavity interactions, while ionization potentials (IPs) are less sensitive to the presence of the cavity. The predicted EAs by QED-CC theory can be reduced by up to 0.22 eV when considering experimentally accessible coupling parameters.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
James K. Freericks
Summary: This work presents a method to relate the UNITARY COPLED CLUSTER approximation to the conventional COUPLED CLUSTER approximation, by manipulating operators. The factorized form of the approximations can be transformed using exponential disentangling identity and Hadamard lemma, and further related to the standard form using the Trotter product formula. The dependence on operators can also be removed by introducing higher-rank operators, yielding the conventional COUPLED CLUSTER method.
Article
Chemistry, Physical
Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL PHYSICS
(2019)
Article
Chemistry, Physical
Armin Khamoshi, Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL PHYSICS
(2019)
Article
Chemistry, Physical
Gaurav Harsha, Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2019)
Article
Chemistry, Physical
Gaurav Harsha, Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Rishab Dutta, Thomas M. Henderson, Gustavo E. Scuseria
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2020)
Article
Chemistry, Physical
Armin Khamoshi, Guo P. Chen, Thomas M. Henderson, Gustavo E. Scuseria
Summary: Single-reference methods like Hartree-Fock coupled cluster theory are accurate for weakly correlated systems, but more sophisticated methods are needed for strongly correlated systems. Recent studies have shown the potential of antisymmetrized geminal power (AGP) as a good initial reference for strong correlation. This paper explores non-linear exponential Ansatz for improving AGP and investigates two approaches, with benchmark calculations against the ground state of the pairing Hamiltonian.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Rishab Dutta, Guo P. Chen, Thomas M. Henderson, Gustavo E. Scuseria
Summary: The paper demonstrates the construction of a linearly independent set of antisymmetrized geminal power (AGP) states and how to rewrite geminal replacement models as linear combinations of non-orthogonal AGPs, simplifying the evaluation of matrix elements. It introduces an AGP-based selective configuration interaction method that allows reaching arbitrary excitation levels relative to a reference AGP, balancing accuracy and cost effectively.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Ruiheng Song, Thomas M. Henderson, Gustavo E. Scuseria
Summary: The study presents an alternative approach to address the connection between weakly correlated and strongly correlated systems, and shows promising results.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Athanasios Papastathopoulos-Katsaros, Carlos A. Jimenez-Hoyos, Thomas M. Henderson, Gustavo E. Scuseria
Summary: We introduce perturbation and coupled-cluster theories based on a cluster mean-field reference for describing the ground state of strongly correlated spin systems. The methods presented can provide a relatively accurate description of the Heisenberg model in the regimes considered and can be used for other strongly correlated systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Thomas. M. M. Henderson, Guo P. Chen, Gustavo. E. E. Scuseria
Summary: The Jordan-Wigner transformation establishes a duality between su(2) and fermionic algebras. When mapping spins to fermions, the transformation weakens strong correlation, while mapping fermions to qubits strengthens strong correlation.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Review
Chemistry, Physical
Gaurav Harsha, Thomas M. Henderson, Gustavo E. Scuseria
Summary: Wave function methods provide a reliable approach to study ground-state properties in quantum many-body systems. However, methods to study thermal properties have been lacking due to the difficulty of evaluating thermal properties involving the entire Hilbert space. In this review, we present a finite-temperature wave function formalism based on thermofield dynamics, which allows mapping the thermal density matrix to a pure state and generalizing ground-state wave function theories to finite temperatures.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Physical
Athanasios Papastathopoulos-Katsaros, Thomas M. Henderson, Gustavo E. Scuseria
Summary: We introduce S(z) spin-projection based on cluster mean-field theory and apply it to strongly correlated spin systems. By removing the restriction of S-z symmetry adaptation, we propose a generalized cluster mean-field theory that allows each cluster to access all S-z sectors. A projection scheme is used to restore global S-z, resulting in the Sz spin-projected generalized cluster mean-field method. These methods provide a qualitative and semi-quantitative description of Heisenberg lattices, suggesting their usefulness for studying inter-cluster correlations.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Gaurav Harsha, Yi Xu, Thomas M. Henderson, Gustavo E. Scuseria
Summary: In this paper, a formulation of thermal CC for SU(2) systems is provided and applied to the Lipkin-Meshkov-Glick system and one-dimensional transverse field Ising model as benchmark applications, highlighting the accuracy of thermal CC in studying finite-temperature phase diagrams in SU(2) systems.
Article
Physics, Nuclear
Y. Qiu, T. M. Henderson, T. Duguet, G. E. Scuseria