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Showing 1 to 20 of 26 for “"Ccsd(T)"”.

  1. It's Not a SKZCAM! Accurate Surface Chemistry at Low Cost

    Shi, Benjamin XuUniversity of Cambridge2024

    … double, and perturbative triple excitations [CCSD(T)]. However, the high computational cost of CCSD(T) typically necessitates the use of embedded cluster models, where the surface is modelled as a finite cluster [treated with CCSD(T)] that is coupled to the environment. Unfortunately, …

    cambridge Repository record

  2. Efficient Prediction of Quantum Chemical Properties with Multitask Gaussian Process Regression

    Fisher, KatharineMassachusetts Institute of Technology2023

    … access to a limited amount of highly accurate CCSD(T) data as well as data obtained using a range of approximations to the exchange-correlation functional in density functional theory (DFT). A CCSD(T) calculation can incur 1000 to one million times the computational cost of a DFT calculation, …

    mit Repository record

  3. Efficient automated implementation of higher-order many-body methods in quantum chemistry

    Teke, Nakul KushabhauVirginia Tech2023

    … almost always more accurate (with respect to the CCSDTQ reference) than the CCSDT model as well as the standard CCSD(T) model. The mean errors in { 3CC, CCSDT, and CCSD(T) } electronic (per valence electron) and atomization energies were {23, 69, 125} μEh/e and {0.39, 1.92, 2.57} kJ/mol, …

    vt Repository record

  4. QUANTUM OBSERVABLES OF OPEN-SHELL SYSTEMS. A THEORETICAL STUDY

    BRUNO, GIOVANNAUniversità degli Studi di Milano2022

    … orbital (DLPNO) variant of the “gold standard” CCSD(T) method for the prediction of phosphorescence energies of aromatic chromophores is investigated for the first time [2]. An extensive analysis of both accuracy and computational cost of the main parameters of the method (basis set, triples …

    milano Repository record

  5. Accurate Calculations of Molecular Properties with Explicitly Correlated Methods

    Zhang, JinmeiVirginia Tech2014

    … of the perturbative coupled-cluster F12 method, CCSD(T)F12, developed in our group for the treatment of high-spin open-shell molecules (J. Zhang and E. F. Valeev, J. Chem. Theory Comput., 2012, 8, 3175.), is also documented. Its performance is assessed for accurate prediction of chemical …

    vt Repository record

  6. Comparison of Calculated Normal Mode Molecular Vibrations with Experimental Gas-Phase Infrared Spectroscopy

    Sutar, Anila Renis2021

    … sets), such as, B3LYP-D/cc-pVDZ, MP2-cc-pVDZ, CCSD/cc-pVDZ, CCSD(T)/aug-cc-pVDZ, CCSD(T)/aug-cc-pVTZ, CCSD/cc-pVDZ and CCSD/cc-pVTZ on different diatomic and polyatomic molecules using the <em>ab initio</em> computational software package, Psi4. H<sub>2</sub>, C<sub>2</sub>, HCl and CO required …

    cuny Repository record

  7. Structure, heats of formation, and bond dissociation energies of group IIIa-group IVA-group VA molecules for chemical hydrogen storage systems

    Grant, Daniel JustinUniversity of Alabama Libraries2010

    … and bond dissociation energies (BDEs), from CCSD(T) calculations in conjunction with correlation consistent basis sets extrapolated to the complete basis set limit, including additional core-valence, scalar-relativistic, and atomic spin-orbit corrections. Geometry optimizations and …

    alabama Repository record

  8. Coupled-Cluster Methods for Large Molecular Systems Through Massive Parallelism and Reduced-Scaling Approaches

    Peng, ChongVirginia Tech2018

    … doubles, and perturbative triples model (CCSD(T)), which is known as the ``gold standard" of quantum chemistry for its accuracy, usually can treat molecules with 20-30 atoms. To extend the reach of accurate correlated electronic structure methods to larger molecular systems, we work …

    vt Repository record

  9. Data-driven models of water and methane

    Szekely, EszterUniversity of Cambridge2021

    … the model based on PIPs. As the fitted level, CCSD(T)-F12, is not applicable to larger systems, we compare the calculations to DMC results for the larger clusters and periodic systems. However, small systematic differences are found between the developed models and DMC; comparing different …

    cambridge Repository record

  10. Investigations of Thermochemistry and the Kinetics of H Atom Radical Reactions

    Peebles, Lynda ReneeUniversity of North Texas2002

    … with sulfur and oxygen were studied via CCSD(T) theory, together with extrapolation to the complete basis set limit. The results for the bond dissociation energies (ground state at 0 K, units: kJ mol-1) are: S-H = 349.9, S-D = 354.7, HS-H = 376.2, DS-D = 383.4, and HO-H = 492.6. These …

    unt Repository record

  11. Theoretical Characterization of Non-Covalent Weakly Bound Clusters Through the Application of Sophisticated Computational Quantum Chemistry Methodologies and the Development of Integrated Fragmentation Techniques

    Bates, Desiree2019

    … systems at greatly reduced computational costs. CCSD(T) complete basis set limit interaction energies are presented for a variety of parallel-slipped &pi;...&pi; dimers and low-lying isomers of (h<sub>2</sub>o)<sub>6</sub>. The calibration of a 2-body:Many-body fragmentation method for computing …

    mississippi Repository record

  12. Development and Application of Coupled Cluster Ground- and Excited-State Models

    Smith, Christopher EdwardVirginia Tech2006

    … delocalization of the monocyclic form. At the CCSDT/6-31G** level of theory, the C1–C3 distance of the minimum energy form of m-benzyne is 2.0°A and the profile of the PES along the C1–C3 distance is that of an asymmetric, single-well, in agreement with previous density-functional theory and …

    vt Repository record

  13. Accurate Computation Of Molecular Properties From Novel Applications Of Quantum Mechanical Wavefunction Methods

    Howard, James Coleman2019

    … of correlated wavefunction methods, the ccsd(t) method, but with much greater efficiency. In addition, this work includes careful calibration studies to examine the basis set convergence of harmonic frequencies to determine which basis sets can be employed to obtain ab initio frequencies …

    mississippi Repository record

  14. A computational study of acidic Ionic Liquids for cellobiose hydrolysis in ionic liquids

    Nel, Jessica LiséDepartment of Chemistry2019

    … thermodynamic cycle protocol, a DLPNO-CCSD(T)/ccpVTZ//TPSS/def2-TZVP [M05-2X/6-31+G** (SMD)] proton exchange cycle, was established through benchmarking for the prediction of Brønsted acid-functionalised ionic liquid pKa values in ionic liquids. The sulfonyl-functionalised acidic IL was …

    cape-town Repository record

  15. Predicting organosulfur chemistry in fuel sources

    Class, Caleb AndrewMassachusetts Institute of Technology2015

    … quantum chemical calculations at the CBS-QB3 and CCSD(T)-F12 levels of theory. With these data, as well as previously calculated rates for hydrocarbon and sulfur kinetics, RMG is used to build a reaction mechanism for the conversion of hexyl sulfide to hydrogen sulfide, pentane, and carbon …

    mit Repository record

  16. Towards exact molecular dynamics simulations with invariant machine-learned models

    Chmiela, Stefan2019

    … global force fields at quantum-chemical CCSD(T) level of accuracy and allows converged MD simulations with fully quantized electrons and nuclei. We present MD simulations, for flexible molecules with up to a few dozen atoms and provide insights into the dynamical behavior of these …

    tu-berlin Repository record

  17. Química organometálica en disolución acuosa: Estudio teórico de reacciones catalizadas por molibdenos y complejos de paladio

    Tilvez Marrugo, Elkin Alberto2014

    … a métodos basados en la función de onda (MP2 y CCSD(T))). Los átomos no metálicos de los diferentes sistemas estudiados han sido descritos mediante funciones de base consistentes con la correlación de calidad doble-zeta y triple-zeta desarrolladas por Dunning. Para los metales molibdeno y …

    oviedo Repository record

  18. Theoretical study of nanocrystals and other functional nanostructures of silicon and alternative group - 14 elements

    Niaz, Shanawer2015

    … perturbation theory (MP2) or Coupled cluster CCSD(T), for comparison. For the study of Si and Ge nanowires we have also used properly selected (and tested) semiempirical methods and calculations. These theoretical methods and techniques are reviewed in considerable detail in the first three …

    patras-thes Repository record

  19. Towards a Reduced-Scaling Method for Calculating Coupled Cluster Response Properties

    Kumar, AshutoshVirginia Tech2018

    … with the perturbative inclusion of triples: the CCSD(T) model, which is considered to be the ``gold standard'' of quantum chemistry scales as 𝑂(N⁷) in its canonical formulation, where $N$ is a measure of the system size. However, the steep scaling associated with these methods is unphysical since …

    vt Repository record

  20. In Pursuit of Local Correlation for Reduced-Scaling Electronic Structure Methods in Molecules and Periodic Solids

    Clement, Marjory CarolenaVirginia Tech2021

    … doubles, and perturbative triples method [CCSD(T)], which is frequently referred to as the "gold standard" of quantum chemistry, has an N⁷ scaling, making it inapplicable to many systems of real-world import. If highly accurate correlated wavefunction methods are to be applied to larger …

    vt Repository record

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