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The present work proposes to use density-functional theory (DFT) to correct for the basis-set error of wave-function theory (WFT). One of the key ideas developed here is to define a range-separation parameter which automatically adapts to a…

In recent years, nonlinear model predictive control (NMPC) has been extensively used for solving automotive motion control and planning tasks. In order to formulate the NMPC problem, different coordinate systems can be used with different…

Systems and Control · Electrical Eng. & Systems 2022-12-27 Rudolf Reiter , Armin Nurkanović , Jonathan Frey , Moritz Diehl

We present an ab-initio dynamical configuration interaction (DCI) study of free- and Mg-porphyrin. DCI is a recently developed active space theory based on the L\"owdin downfolding technique. In the active space, static correlation is…

Materials Science · Physics 2020-06-18 Marc Dvorak , Patrick Rinke

We consider pairwise interaction energies and we investigate their minimizers among lattices with prescribed minimal vectors (length and coordination number), i.e. the one corresponding to the crystal's bonds. In particular, we show the…

Mathematical Physics · Physics 2021-09-20 Laurent Bétermin

Current Non-Orthogonal Configuration Interaction (NOCI) methods often use a set of Self-Consistent Field (SCF) states selected based on chemical intuition. However, it may be challenging to track these SCF states across a dissociation…

Chemical Physics · Physics 2021-12-15 Nicholas Lee , Alex J. W. Thom

This work develops and illustrates a new method of calculating "chemically accurate" electronic wavefunctions (and energies) via a truncated full configuration interaction (CI) procedure which arguably circumvents the large matrix…

Chemical Physics · Physics 2022-12-21 Stephen J. Cotton

We identify the dominant computational cost within the recently introduced stochastic and internally contracted FCIQMC-NEVPT2 method for large active space sizes. This arises from the contribution to the four-body intermediates arising from…

Chemical Physics · Physics 2020-10-05 James J. Halson , Robert J. Anderson , George H. Booth

We present NECI, a state-of-the-art implementation of the Full Configuration Interaction Quantum Monte Carlo algorithm, a method based on a stochastic application of the Hamiltonian matrix on a sparse sampling of the wave function. The…

We introduce affordable computational strategies for calculating orbital and pair-orbital energies in atomic and molecular systems. Our methods are based on the pair Coupled Cluster Doubles (pCCD) ansatz and its orbital-optimized variant.…

Chemical Physics · Physics 2025-02-06 Seyedehdelaram Jahani , Somayeh Ahmadkhani , Katharina Boguslawski , Paweł Tecmer

In this work we demonstrate how to compute the one- and two-body reduced density matrices within the spin-adapted full configuration interaction quantum Monte Carlo (FCIQMC) method, which is based on the graphical unitary group approach…

Chemical Physics · Physics 2021-09-27 Werner Dobrautz , Oskar Weser , Nikolay Bogdanov , Ali Alavi , Giovanni Li Manni

Accurate calculations of strongly correlated materials remain a formidable challenge in condensed matter physics, particularly due to the computational demand of conventional methods. This paper presents an efficient solver for dynamical…

Strongly Correlated Electrons · Physics 2025-12-04 Basile Herzog , Patrik Thunström , Olle Eriksson

We provide an accurate calculation of the energy spectrum of three atoms interacting through a contact force in a one-dimensional harmonic trap, considering both spinful fermions and spinless bosons. We use fermionic energies as a benchmark…

Quantum Gases · Physics 2014-03-04 Pino D'Amico , Massimo Rontani

Circular colliders have the advantage of delivering collisions to multiple interaction points, which allow different detector designs to be studied and optimized - up to four for FCC-ee. On the one hand, the detectors must satisfy the…

High Energy Physics - Experiment · Physics 2021-07-12 Patrizia Azzi , Emmanuel Perez

We present a quantum algorithm for the simulation of molecular systems that is asymptotically more efficient than all previous algorithms in the literature in terms of the main problem parameters. As in previous work [Babbush et al., New…

Feedback-based quantum algorithms have recently emerged as potential methods for approximating the ground states of Hamiltonians. One such algorithm, the feedback-based algorithm for quantum optimization (FALQON), is specifically designed…

Quantum Physics · Physics 2025-08-18 Salahuddin Abdul Rahman , Özkan Karabacak , Rafal Wisniewski

The dynamic set cover problem has been subject to extensive research since the pioneering works of [Bhattacharya et al, 2015] and [Gupta et al, 2017]. The input is a set system $(U, S)$ on a fixed collection $S$ of sets and a dynamic…

Data Structures and Algorithms · Computer Science 2024-10-29 Anton Bukov , Shay Solomon , Tianyi Zhang

Exact solutions for local equilibrium and nonequilibrium out-of-time-ordered correlation (OTOC) functions are obtained for a lattice fermion model with on-site interactions, namely the Falicov-Kimball (FK) model, in the large dimensional…

Quantum Gases · Physics 2017-02-13 Naoto Tsuji , Philipp Werner , Masahito Ueda

We study the optimal transport problem for pairs of stationary finite-state Markov chains, with an emphasis on the computation of optimal transition couplings. Transition couplings are a constrained family of transport plans that capture…

Optimization and Control · Mathematics 2021-09-20 Kevin O'Connor , Kevin McGoff , Andrew B. Nobel

This contribution compiles the benefits of lattice symmetry in the context of closed orbit correction. A symmetric arrangement of BPMs and correctors results in structured orbit response matrices of Circulant or block Circulant type. These…

Accelerator Physics · Physics 2019-07-31 Sajjad Hussain Mirza , Rahul Singh , Peter Forck , Harald Klingbeil

Molecule-optimized basis sets, based on approximate natural orbitals, are developed for accelerating the convergence of quantum calculations with strongly correlated (multi-referenced) electrons. We use a low-cost approximate solution of…

Chemical Physics · Physics 2014-02-12 Gergely Gidofalvi , David A. Mazziotti