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Functional connectivity (FC) is one of the most common inputs to fMRI-based predictive models, due to a combination of its simplicity and robustness. However, there may be a lack of theoretical models for the generation of FC. In this work,…

Neurons and Cognition · Quantitative Biology 2023-05-19 Anton Orlichenko , Gang Qu , Ziyu Zhou , Zhengming Ding , Yu-Ping Wang

A recent direction in quantum computing for molecular electronic structure sees the use of quantum devices as configuration sampling machines integrated within high-performance computing (HPC) platforms. This appeals to the strengths of…

Quantum Physics · Physics 2026-05-18 Tim Weaving , Angus Mingare , Alexis Ralli , Peter V. Coveney

Integrating multiple functionalities into a single metasurface is becoming of great interest for future intelligent communication systems. While such devices have been extensively explored for reciprocal functionalities, in this work, we…

Applied Physics · Physics 2020-11-23 Xuchen Wang , Ana Diaz-Rubio , Huanan Li , Sergei A. Tretyakov , Andrea Alu

We present a perspective on what the future holds for full configuration interaction (FCI) theory, with an emphasis on conceptual rather than technical details. Upon revisiting the early history of FCI, a number of its key contemporary…

Chemical Physics · Physics 2020-12-29 Janus J. Eriksen

The potential energy curve of the F$_2$ molecule is calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC) using Configuration Interaction (CI)-type trial wavefunctions. To keep the number of determinants reasonable (the first and second…

Chemical Physics · Physics 2016-07-25 Emmanuel Giner , Anthony Scemama , Michel Caffarel

Direct approaches to the quantum many-body problem suffer from the so-called "curse of dimensionality": the number of parameters needed to fully specify the exact wavefunction grows exponentially with increasing system size. This motivates…

Quantum Physics · Physics 2023-04-21 Valerii Chuiko , Paul W. Ayers

We introduce a new procedure for iterative selection of determinant spaces capable of describing highly correlated systems. This adaptive configuration interaction (ACI) determines an optimal basis by an iterative procedure in which the…

Chemical Physics · Physics 2016-05-25 Jeffrey B. Schriber , Francesco A. Evangelista

A major challenge in modern physics is to accurately describe strongly interacting quantum many-body systems. One-dimensional systems provide fundamental insights since they are often amenable to exact methods. However, no exact solution is…

Quantum Gases · Physics 2015-07-28 Jesper Levinsen , Pietro Massignan , Georg M. Bruun , Meera M. Parish

Component substitution has numerous practical applications and constitutes an active research topic. This paper proposes to enrich an existing component-based framework--a model with dynamic reconfigurations making the system evolve--with a…

Software Engineering · Computer Science 2014-08-10 Arnaud Lanoix , Olga Kouchnarenko

Even when starting with a very poor initial guess, the iterative configuration interaction (iCI) approach can converge from above to full CI very quickly by constructing and diagonalizing a small Hamiltonian matrix at each…

Chemical Physics · Physics 2020-01-07 Ning Zhang , Wenjian Liu , Mark R. Hoffmann

Solving for the many-body wavefunction represents a significant challenge on both classical and quantum devices because of the exponential scaling of the Hilbert space with system size. While the complexity of the wavefunction can be…

Quantum Physics · Physics 2025-05-06 Yuchen Wang , David A. Mazziotti

We present a new quantum embedding theory called dynamical configuration interaction (DCI) that combines wave function and Green's function theories. DCI captures static correlation in a correlated subspace with configuration interaction…

Chemical Physics · Physics 2019-11-21 Marc Dvorak , Dorothea Golze , Patrick Rinke

The Theory of Functional Connections (TFC) is a functional interpolation framework founded upon the so-called constrained expression: a functional that expresses the family of all possible functions that satisfy some user-specified, linear…

Analysis of PDEs · Mathematics 2021-10-25 Carl Leake

An externally corrected coupled cluster (CC) method, where an adaptive configuration interaction (ACI) wave function provides the external cluster amplitudes, named ACI-CC, is presented. By exploiting the connection between configuration…

Chemical Physics · Physics 2023-09-27 Gustavo J. R. Aroeira , Madeline M. Davis , Justin M. Turney , Henry F. Schaefer

We introduce the pCI software package for high-precision atomic structure calculations. The standard method of calculation is based on the configuration interaction (CI) method to describe valence correlations, but can be extended to attain…

Facilitated by a rigorous partitioning of a molecular system's orbital basis into two fundamental subspaces - a reference and an expansion space, both with orbitals of unspecified occupancy - we generalize our recently introduced many-body…

Chemical Physics · Physics 2019-12-12 Janus J. Eriksen , Jürgen Gauss

The antisymmetrized geminal power (AGP) wave function has a long history and considerable conceptual appeal, but in many situations its accuracy is wanting. Here, we consider a form of configuration interaction (CI) based upon the AGP wave…

Chemical Physics · Physics 2020-05-14 Thomas M. Henderson , Gustavo E. Scuseria

Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid…

General Relativity and Quantum Cosmology · Physics 2015-12-02 Liang Dai , Enrico Pajer , Fabian Schmidt

We introduce vibrational heat-bath configuration interaction (VHCI) as an accurate and efficient method for calculating vibrational eigenstates of anharmonic systems. Inspired by its origin in electronic structure theory, VHCI is a selected…

Chemical Physics · Physics 2021-03-17 Jonathan H. Fetherolf , Timothy C. Berkelbach

Integrated sensing and communication (ISAC) emerges as an essential technique for overcoming spectrum congestion. However, the performance of traditional ISAC systems with fixed-position-antennas (FPA) is limited due to insufficient spatial…

Signal Processing · Electrical Eng. & Systems 2024-07-30 Tian Hao , Changxin Shi , Qingqing Wu , Bin Xia , Yinghong Guo , Lianghui Ding , Feng Yang