Coupled Cluster Methods

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Karol Kowalski - One of the best experts on this subject based on the ideXlab platform.

  • implementation of high order multireference Coupled Cluster Methods on intel many integrated core architecture
    Journal of Chemical Theory and Computation, 2016
    Co-Authors: Edoardo Apra, Karol Kowalski
    Abstract:

    In this paper we discuss the implementation of multireference Coupled-Cluster formalism with singles, doubles, and noniterative triples (MRCCSD(T)), which is capable of taking advantage of the processing power of the Intel Xeon Phi coprocessor. We discuss the integration of two levels of parallelism underlying the MRCCSD(T) implementation with computational kernels designed to offload the computationally intensive parts of the MRCCSD(T) formalism to Intel Xeon Phi coprocessors. Special attention is given to the enhancement of the parallel performance by task reordering that has improved load balancing in the noniterative part of the MRCCSD(T) calculations. We also discuss aspects regarding efficient optimization and vectorization strategies.

  • poster utilizing dataflow based execution for Coupled Cluster Methods
    International Conference on Cluster Computing, 2014
    Co-Authors: Heike Mccraw, Karol Kowalski, Anthony Danalis, Thomas Herault, George Bosilca, Jack Dongarra, Theresa L Windus
    Abstract:

    Computational chemistry comprises one of the driving forces of High Performance Computing. In particular, many-body Methods, such as Coupled Cluster Methods (CC) [1] of the quantum chemistry package NWCHEM [2], are of particular interest for the applied chemistry community.

  • utilizing dataflow based execution for Coupled Cluster Methods
    International Conference on Cluster Computing, 2014
    Co-Authors: Heike Mccraw, Karol Kowalski, Anthony Danalis, Thomas Herault, George Bosilca, Jack Dongarra, Theresa L Windus
    Abstract:

    Computational chemistry comprises one of the driving forces of High Performance Computing. In particular, many-body Methods, such as Coupled Cluster Methods (CC) [1] of the quantum chemistry package NWCHEM [2], are of particular interest for the applied chemistry community.

  • equation of motion Coupled Cluster Methods for electron attachment and ionization potential in fullerenes c60 and c70
    Journal of Chemical Physics, 2014
    Co-Authors: Kiran Bhaskarannair, Karol Kowalski, Juana Moreno, Mark Jarrell, William A Shelton
    Abstract:

    In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the Coupled Cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C60 and C70. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations.

  • Cluster - Utilizing Dataflow-Based Execution for Coupled Cluster Methods
    2014 IEEE International Conference on Cluster Computing (CLUSTER), 2014
    Co-Authors: Heike Mccraw, Karol Kowalski, Anthony Danalis, Thomas Herault, George Bosilca, Jack Dongarra, Theresa L Windus
    Abstract:

    Computational chemistry comprises one of the driving forces of High Performance Computing. In particular, many-body Methods, such as Coupled Cluster Methods (CC) [1] of the quantum chemistry package NWCHEM [2], are of particular interest for the applied chemistry community.

Rodney J. Bartlett - One of the best experts on this subject based on the ideXlab platform.

  • explicitly correlated double ionization potentials and double electron attachment equation of motion Coupled Cluster Methods
    Chemical Physics Letters, 2018
    Co-Authors: Denis Bokhan, Ajith Perera, D N Trubnikov, Rodney J. Bartlett
    Abstract:

    Abstract Double ionization and double electron attachment equation-of-motion Methods, based on linearly approximated explicitly correlated Coupled-Cluster singles and doubles [CCSD(F12)] are formulated and implemented. An extension of double electron attachment operator is introduced for proper account of short-range correlation effects in states with two additional electrons. Numerical tests for set of doubly ionized and doubly electron attached states of several molecules have shown a good agreement between obtained explicitly-correlated results and the corresponding complete basis set limit values already at double- ζ level.

  • excited states from modified Coupled Cluster Methods are they any better than eom ccsd
    Journal of Chemical Physics, 2017
    Co-Authors: Varun Rishi, Ajith Perera, Marcel Nooijen, Rodney J. Bartlett
    Abstract:

    Simplifications or modifications of Coupled Cluster Methods such as the CCSD (Coupled Cluster singles and doubles) model often perform better than the original method in providing the total energy, equilibrium geometries, and harmonic vibration frequencies for the ground state. Three such Methods that have been recently proposed include 2CC, parameterized CCSD generalizations, and distinguishable Cluster singles and doubles (DCSD) approach. In this paper, we lay the theoretical foundation needed to treat excited states via the equation of motion (EOM) approach using these ground state CC Methods. As these ground state approximations to CCSD share its property of being exact for two-electron systems, so will their excited state extensions. These Methods are tested for two complementary benchmark sets of excited states for a wide range of organic molecules with focus on singlet and triplet excited states of both valence and Rydberg nature. We also test these Methods for doubly excited states, taking CH+ as an example to test their performance at equilibrium and stretched bond geometries. Finally, we assess if any of these Methods perform consistently better than EOM CCSD.

  • spectroscopic analysis of diphosphatriazolate anion p2n3 by Coupled Cluster Methods as a step toward n5
    Chemical Physics Letters, 2015
    Co-Authors: Yifan Jin, Rodney J. Bartlett, Ajith Perera
    Abstract:

    The long sought N5− is a step from the recently synthesized aromatic pentagonal diphosphatriazolate anion (P2N3−). As accurate spectroscopic properties of N5− are only known from theoretical calculations, this manuscript demonstrates the accuracy of the computed P2N3− spectra (IR, Raman, and NMR) obtained from Coupled-Cluster Methods [CCSD or CCSD(T)] compared to experiment, eliminating any ambiguities of the prior density functional theory (DFT) results. Excited and ionized state calculations from EOM-CCSD(T) and IP-EOM-CCSD offer predictions of those additional properties. Differences between P2N3− and N5− arise primarily due to the positive electron affinities of P2, which cause very different potential energy surfaces.

  • Singlet–triplet separations of di-radicals treated by the DEA/DIP-EOM-CCSD Methods
    Theoretical Chemistry Accounts, 2014
    Co-Authors: Ajith Perera, Robert W. Molt, Victor F. Lotrich, Rodney J. Bartlett
    Abstract:

    The singlet–triplet splittings of the di-radicals methylene, trimethylene–methane, ortha-, meta- and para-benzynes, and cyclobutane-1,2,3,4-tetrone have become test systems for the applications of various multi-reference (MR) Coupled-Cluster Methods. We report results close to the basis set limit computed with double ionization potential (DIP) and double electron attachment (DEA) equation-of-motion Coupled-Cluster Methods. These di-radicals share the characteristics of a 2-hole 2-particle MR problem and are commonly used to assess the performance of MR Methods, and yet require more careful study unto themselves as benchmarks. Here, using our CCSD(T)/6-311G(2d,2p) optimized geometries, we report DIP/DEA-CC results and single-reference (SR) CCSD, CCSD(T), ΛCCSD(T) and CCSDT results for comparison.

  • Report of a Workshop on Parallelization of Coupled Cluster Methods
    2008
    Co-Authors: Rodney J. Bartlett, Erik Deumens
    Abstract:

    The benchmark, ab initio quantum mechanical Methods for molecular structure and spectra are now recognized to be Coupled-Cluster theory. To benefit from the transiiton to tera- and petascale computers, such Coupled-Cluster Methods must be created to run in a scalable fashion. This Workshop, held as a aprt of the 48th annual Sanibel meeting, at St. Simns, Island, GA, addressed that issue. Representatives of all the principal scientific groups who are addressing this topic were in attendance, to exchange information about the problem and to identify what needs to be done in the future. This report summarized the conclusions of the workshop.

Piotr Piecuch - One of the best experts on this subject based on the ideXlab platform.

  • application of the cc p q hierarchy of Coupled Cluster Methods to the beryllium dimer
    Journal of Physical Chemistry A, 2017
    Co-Authors: Ilias Magoulas, Nicholas P Bauman, Jun Shen, Piotr Piecuch
    Abstract:

    The performance of Coupled-Cluster approaches with higher-than-doubly excited Clusters, including the CCSD(T), CCSD(2)T, CR-CC(2,3), CCSD(TQ), and CR-CC(2,4) corrections to CCSD, the active-space CCSDt, CCSDtq, and CCSDTq Methods, and the CC(t;3), CC(t,q;3), CC(t,q;3,4), and CC(q;4) corrections to CCSDt, CCSDtq, and CCSDTq resulting from the CC(P;Q) formalism, in reproducing the CCSDT and CCSDTQ potential energy curves and vibrational term values characterizing Be2 in its electronic ground state is assessed. The correlation-consistent aug-cc-pVnZ and aug-cc-pCVnZ (n = T and Q) basis sets are employed. Among the CCSD-based corrections, the completely renormalized CR-CC(2,3) and CR-CC(2,4) approaches perform the best. The CC(t;3), CC(t,q;3), CC(t,q;3,4), and CC(q;4) Methods, especially CC(t;3) and CC(q;4), outperform other employed approaches in reproducing the CCSDT and CCSDTQ data. Composite schemes combining the all-electron CCSDT calculations extrapolated to the complete basis set limit with the frozen-...

  • active space Coupled Cluster Methods
    Molecular Physics, 2010
    Co-Authors: Piotr Piecuch
    Abstract:

    Active-space Coupled-Cluster (CC) Methods, including their origin and recent developments, are reviewed, and further challenges in this area are briefly discussed. The focus is on the significance of the paper by Professors Stanislaw A. Kucharski and Rodney J. Bartlett, and the author of the present article [J. Chem. Phys. 110, 6103 (1999)], written when the author of the present article was a member of Professor Rodney J. Bartlett's research group at Quantum Theory Project. It is argued that that paper has played an important role in bringing the idea of selecting higher-than-double excitations within the single-reference CC framework to mimic multi-reference theories, proposed earlier [N. Oliphant and L. Adamowicz, J. Chem. Phys. 94, 1229 (1991); P. Piecuch et al., J. Chem. Phys. 99, 1875 (1993)], to the forefront of quantum chemistry development work, while inspiring extensions of such Methods to electronically excited states and valence systems around closed shells via the equation-of-motion CC theory.

  • renormalized Coupled Cluster Methods exploiting left eigenstates of the similarity transformed hamiltonian
    Journal of Chemical Physics, 2005
    Co-Authors: Piotr Piecuch, Marta Wloch
    Abstract:

    Completely renormalized (CR) Coupled-Cluster (CC) approaches, such as CR-CCSD(T), in which one corrects the standard CC singles and doubles (CCSD) energy for the effects of triply (T) and other higher-than-doubly excited Clusters [K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000)], are reformulated in terms of the left eigenstates ⟨Φ∣L of the similarity-transformed Hamiltonian of CC theory. The resulting CR-CCSD(T)L or CR-CC(2,3) and other CR-CCL Methods are derived from the new biorthogonal form of the method of moments of CC equations (MMCC) in which, in analogy to the original MMCC theory, one focuses on the noniterative corrections to standard CC energies that recover the exact, full configuration-interaction energies. One of the advantages of the biorthogonal MMCC theory, which will be further analyzed and extended to excited states in a separate paper, is a rigorous size extensivity of the basic ground-state CR-CCL approximations that result from it, which was slightly violated by the origin...

  • extension of renormalized Coupled Cluster Methods including triple excitations to excited electronic states of open shell molecules
    Journal of Chemical Physics, 2005
    Co-Authors: Marta Wloch, Karol Kowalski, Jeffrey R Gour, Piotr Piecuch
    Abstract:

    The general-purpose open-shell implementation of the completely renormalized equation-of-motion Coupled-Cluster approach with singles, doubles, and noniterative triples [CR-EOMCCSD(T)] is reported. Benchmark calculations for the low-lying doublet and quartet states of the CH radical show that the CR-EOMCCSD(T) method is capable of providing a highly accurate description of ground and excited states of open-shell molecules. This includes states with strong double excitation character, for which the conventional EOMCCSD approach fails.

  • extensive generalization of renormalized Coupled Cluster Methods
    Journal of Chemical Physics, 2005
    Co-Authors: Karol Kowalski, Piotr Piecuch
    Abstract:

    The recently developed completely renormalized (CR) Coupled-Cluster (CC) Methods with singles, doubles, and noniterative triples or triples and quadruples [CR-CCSD(T) or CR-CCSD(TQ), respectively], which are based on the method of moments of CC equations (MMCC) [K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000)], eliminate the failures of the standard CCSD(T) and CCSD(TQ) Methods at larger internuclear separations, but they are not rigorously size extensive. Although the departure from strict size extensivity of the CR-CCSD(T) and CR-CCSD(TQ) Methods is small, it is important to examine the possibility of formulating the improved CR-CC Methods, which are as effective in breaking chemical bonds as the existing CR-CCSD(T) and CR-CCSD(TQ) approaches, which are as easy to use as the CR-CCSD(T) and CR-CCSD(TQ) Methods, and which can be made rigorously size extensive. This may be particularly useful for the applications of CR-CC Methods and other MMCC approaches in calculations of potential energy surfa...

Theresa L Windus - One of the best experts on this subject based on the ideXlab platform.

Jiři Pittner - One of the best experts on this subject based on the ideXlab platform.

  • implementation of the multireference brillouin wigner and mukherjee s Coupled Cluster Methods with non iterative triple excitations utilizing reference level parallelism
    Journal of Chemical Physics, 2012
    Co-Authors: Kiran Bhaskarannair, Jiři Pittner, Jiři Brabec, Edoardo Apra, Hubertus Van Dam, Karol Kowalski
    Abstract:

    In this paper we discuss the performance of the non-iterative state-specific multireference Coupled Cluster (SS-MRCC) Methods accounting for the effect of triply excited Cluster amplitudes. The corrections to the Brillouin-Wigner and Mukherjee's MRCC models based on the manifold of singly and doubly excited Cluster amplitudes (BW-MRCCSD and Mk-MRCCSD, respectively) are tested and compared with exact full configuration interaction results for small systems (H2O, N2, and Be3). For the larger systems (naphthyne isomers) the BW-MRCC and Mk-MRCC Methods with iterative singles, doubles, and non-iterative triples (BW-MRCCSD(T) and Mk-MRCCSD(T)) are compared against the results obtained with single reference Coupled Cluster Methods. We also report on the parallel performance of the non-iterative implementations based on the use of processor groups.

  • recent progress in Coupled Cluster Methods theory and applications
    2010
    Co-Authors: Petr Carský, Josef Paldus, Jiři Pittner
    Abstract:

    The Yearn to be Hermitian (Rodney J. Bartlett, Monika Musial, Victor Lotrich, and Tomasz Kus).- Reduced-Scaling Coupled-Cluster Theory for Response Properties of Large Molecules (T. Daniel Crawford).- Development and Applications of Non-perturbative Approximants to the State-Specific Multi-reference Coupled Cluster Theory: The Two Distinct Variants (Sanghamitra Das, Shubhrodeep Pathak, Rahul Maitra and Debashis Mukherjee).- Development of SAC-CI general-R method for Theoretical Fine Spectroscopy (Masahiro Ehara and Hiroshi Nakatsuji).- Relativistic four-component multireference Coupled Cluster Methods (Ephraim Eliav and Uzi Kaldor).- Block Correlated Coupled Cluster Theory with a Complete Active-Space Self-Consistent-Field Reference Function: The General Formalism and Applications (Tao Fang, Jun Shen, and Shuhua Li).- A Possibility for a Multi-Reference Coupled-Cluster: the MRexpT Ansatz (Michael Hanrath).- Eclectic Electron-Correlation Methods (So Hirata, Toru Shiozaki, Edward F. Valeev, and Marcel Nooijen).- Electronic Excited States in the State-Specific Multireference Coupled Cluster Theory with a Complete-Active-Space Reference. (Vladimir V. Ivanov, Dmitry I. Lyakh and Ludwik Adamowicz).- Multireference R12 Coupled Cluster Theory. (Stanislav Kedzuch, Ondrej Demel, Jiri Pittner and Jozef Noga.- Coupled Cluster treatment of intramonomer correlation effects in intermolecular interactions (Tatiana Korona).- Unconventional Aspects of Coupled-Cluster Theory (Werner Kutzelnigg).- Coupled Clusters and quantum electrodynamics (Ingvar Lindgren, Sten Salomonson, and Daniel Hedendahl).- On some aspects of Fock-space multi-reference Coupled-Cluster singles and doubles energies and optical properties (Prashant Uday Manohar, Kodagenahalli R. Shamasundar, Arijit Bag, Nayana Vaval, and Sourav Pal).- Intermediate Hamiltonian formulations of the Fock-space Coupled-Clustermethod: details, comparisons, examples (Leszek Meissner and Monika Musial).- Coupled Cluster calculations: OVOS as an alternative avenue towards treating still larger molecules (Pavel Neogrady, Michal Pitonak, Jaroslav Granatier and Miroslav Urban).- Multireference Coupled-Cluster Methods: Recent Developments (Josef Paldus, Jiri Pittner, and Petr Carsky).- Vibrational Coupled Cluster Theory (Peter Seidler and Ove Christiansen).- On the Coupled-Cluster equations. Stability analysis and nonstandard correction schemes (Peter R. Surjan and Agnes Szabados).- Explicitly correlated Coupled-Cluster theory (David P. Tew and Christof Hattig and Rafal A. Bachorz and Wim Klopper).- Efficient explicitly correlated Coupled-Cluster approximations (Hans-Joachim Werner, Thomas B. Adler, Gerald Knizia and Frederick R. Manby).- Instability in Chemical Bonds: UNO CASCC, Resonating UCC and Approximately Projected UCC Methods to Quasi-degenerate Electronic Systems. (Shusuke Yamanaka, Satomichi Nishihara, Kazuto Nakata, Yasushige Yonezawa, Yasutaka Kitagawa, Takashi Kawakami, Mitsutaka Okumura, Toshikazu Takada, Haruki Nakamura, and Kizashi Yamaguchi).

  • continuous transition between brillouin wigner and rayleigh schrodinger perturbation theory generalized bloch equation and hilbert space multireference Coupled Cluster
    Journal of Chemical Physics, 2003
    Co-Authors: Jiři Pittner
    Abstract:

    A continuous transition between the Rayleigh–Schrodinger and Brillouin–Wigner perturbation theories is constructed and the Bloch equation for the corresponding wave operator is derived. Subsequently it is applied to the Hilbert space multireference Coupled Cluster theory and used to investigate relationships between several versions of multireference Coupled Cluster Methods. Finally, based on those continuous transitions, new size extensivity corrections for the Brillouin–Wigner Coupled Cluster method are suggested. Numerical tests of size-extensivity and separability of a supermolecule to closed- and open-shell fragments are also presented. Equivalence of some of the multireference Coupled Cluster Methods with single and double excitations to full configuration interaction for two-electron systems is investigated, both theoretically and numerically.

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