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Exceptional points (EP) in non-Hermitian systems have been widely investigated due to their enhanced sensitivity in comparison to standard systems. In this letter, we report the observation of higher-order pseudo-Hermitian degeneracies in…

Applied Physics · Physics 2023-05-02 Ke Yin , Xianglin Hao , Yuangen Huang , Jianlong Zou , Xikui Ma , Tianyu Dong

Heavy polar diatomic molecules are currently among the most promising probes of fundamental physics. Constraining the electric dipole moment of the electron (eEDM), in order to explore physics beyond the Standard Model, requires a synergy…

Atomic Physics · Physics 2018-04-18 M Abe , V S Prasannaa , B P Das

The article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac-Coulomb (DC)…

Chemical Physics · Physics 2020-04-22 Himadri Pathak , Sudip Sasmal , Kaushik Talukdar , Malaya K. Nayak , Nayana Vaval , Sourav Pal

Multi-configurational approaches yield universal wave function parameterizations that can qualitatively well describe electronic structures along reaction pathways. For quantitative results, multi-reference perturbation theory is required…

Chemical Physics · Physics 2016-09-08 Christopher J. Stein , Vera von Burg , Markus Reiher

The complex-scaling method can be used to calculate molecular resonances within the Born-Oppenheimer approximation, assuming the electronic coordinates are dilated independently of the nuclear coordinates. With this method, one will…

Quantum Physics · Physics 2021-06-16 Teng Bian , Sabre Kais

The concept of the effective one-electron potentials (OEP) has been useful for many decades in efficient description of electronic structure of chemical systems, especially extended molecular aggregates such as interacting molecules in…

Chemical Physics · Physics 2020-02-04 Bartosz Błasiak , Joanna D. Bednarska , Marta Chołuj , Wojciech Bartkowiak

The accurate and efficient description of strongly correlated systems remains an important challenge for computational methods. Doubly occupied configuration interaction (DOCI), in which all electrons are paired and no correlations which…

Chemical Physics · Physics 2016-02-25 Thomas M. Henderson , Ireneusz W. Bulik , Gustavo E. Scuseria

We have implemented noniterative triples corrections to the energy from coupled-cluster with single and double excitations (CCSD) within the 1-electron exact two-component (1eX2C) relativistic framework. The effectiveness of both the…

The complex scaling method (CSM) is one of the most powerful methods of describing the resonances with complex energy eigenstates, based on non-Hermitian quantum mechanics. We present the basic application of CSM to the properties of the…

Nuclear Theory · Physics 2020-12-22 Takayuki Myo , Kiyoshi Kato

The accurate description of nuclear quantum effects, such as zero-point energy, is important for modeling a wide range of chemical and biological processes. Within the nuclear-electronic orbital (NEO) approach, such effects are incorporated…

Chemical Physics · Physics 2022-09-07 Fabijan Pavošević , Sharon Hammes-Schiffer

We examine the attosecond electron recollision dissociation of D2+ recently demonstrated experimentally [H. Niikura et al., Nature (London) 421, 826 (2003)] from a coherent control perspective. In this process, a strong laser field incident…

Quantum Physics · Physics 2009-11-13 Michael Spanner , Paul Brumer

We report the results of a first-principles study of dissociative electron attachment to H2O. The cross sections are obtained from nuclear dynamics calculations carried out in full dimensionality within the local complex potential model by…

Chemical Physics · Physics 2007-10-10 Daniel J. Haxton , T. N. Rescigno , C. W. McCurdy

Practical applications of fragment embedding and closely related local correlation methods critically depend on a judicious choice of a low-level theory to define the local embedding subspace and to capture long-range electrostatic and…

Chemical Physics · Physics 2026-05-14 Ruiheng Song , Xiliang Gong , Aamy Bakry , Hong-Zhou Ye

We present a detailed derivation and discussion of cavity Born-Oppenheimer coupled cluster (CBO-CC) theory and address cavity-modified electron correlation in the vibrational strong coupling regime. Methodologically, we combine the recently…

Chemical Physics · Physics 2025-12-02 Eric W. Fischer

Calculations are presented which use the molecular R-matrix with pseudo-states (MRMPS) method to treat electron impact electron detachment and electronic excitation of the carbon dimer anion. Resonances are found above the ionisation…

Atomic Physics · Physics 2010-07-07 Gabriela Halmova , J. D. Gorfinkiel , Jonathan Tennyson

A new perturbative approach to canonical equation-of-motion coupled-cluster theory is presented using coupled-cluster perturbation theory. A second-order M{\o}ller-Plesset partitioning of the Hamiltonian is used to obtain the well known…

Chemical Physics · Physics 2015-07-09 Jason N. Byrd , Varun Rishi , Ajith Perera , Rodney J. Bartlett

The central problem in electronic structure theory is the computation of the eigenvalues of the electronic Hamiltonian -- an unbounded, self-adjoint operator acting on a Hilbert space of antisymmetric functions. Coupled cluster (CC)…

Numerical Analysis · Mathematics 2023-01-30 Muhammad Hassan , Yvon Maday , Yipeng Wang

Electrodynamical coupled cluster (CC) methodologies have been formulated employing standard QED Hamiltonian that is written in Coulomb gauge while using the DF and the MCDF pictures of the matter field for closed-shell and open-shell cases…

Quantum Physics · Physics 2024-01-15 Sambhu N. Datta

In large-scale quantum-chemical calculations the electron-repulsion integral (ERI) tensor rapidly becomes the bottleneck in terms of memory and disk space. When an external finite magnetic field is employed, this problem becomes even more…

Chemical Physics · Physics 2022-02-16 Simon Blaschke , Stella Stopkowicz

The cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction is presented. For large systems, the inclusion of distant pair correlation energies is essential for the accurate…

Chemical Physics · Physics 2020-08-06 Zhigang Ni , Yang Guo , Frank Neese , Wei Li , Shuhua Li
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