Journal ArticleDOI
Low-order scaling local electron correlation methods. V. Connected triples beyond (T): Linear scaling local CCSDT-1b
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In this paper, a new O(N) method for the iterative treatment of connected triple substitutions in the framework of local coupled cluster theory is introduced, which is the local equivalent of the canonical CCSDT-1b method.Abstract:
A new O(N ) method for the iterative treatment of connected triple substitutions in the framework of local coupled cluster theory is introduced here, which is the local equivalent of the canonical CCSDT-1b method. The effect of the triple substitutions is treated in a self-consistent manner in each coupled cluster iteration. As for the local (T) method presented earlier in this series the computational cost of the method scales asymptotically linear with molecular size. The additional computational burden due to the involvement of triples in each coupled cluster iteration hence is not nearly as dramatic as for the parental canonical method, where it implies an increase in the computational complexity of the coupled cluster iteration from O(N6) to O(N7). The method has certain advantages in comparison to the perturbative a posteriori treatment of connected triples (T) for cases where static correlation effects start to play a role. It is demonstrated that molecules with about 100 atoms and 1000 basis funct...read more
Citations
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Molpro: a general-purpose quantum chemistry program package
TL;DR: Molpro (available at http://www.molpro.net) is a general-purpose quantum chemical program as discussed by the authors, which uses local approximations combined with explicit correlation treatments, highly accurate coupled-cluster calculations are now possible for molecules with up to approximately 100 atoms.
Journal ArticleDOI
QM/MM Methods for Biomolecular Systems
Hans Martin Senn,Walter Thiel +1 more
TL;DR: To model large biomolecules the logical approach is to combine the two techniques and to use a QM method for the chemically active region and an MM treatment for the surroundings, enabling the modeling of reactive biomolecular systems at a reasonable computational effort while providing the necessary accuracy.
Journal ArticleDOI
Fast linear scaling second-order Møller-Plesset perturbation theory (MP2) using local and density fitting approximations
TL;DR: It is demonstrated that for large molecules DF-LMP2 is much faster than either LMP2 or DF-MP2 and the errors arising from local approximations are somewhat larger than expected from calculations on smaller systems.
Journal ArticleDOI
Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments
TL;DR: Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments / Albert Rimola;Dominique Costa;Mariona Sodupe;Jean-François Lambert; Piero Ugliengo.
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Efficient and accurate local approximations to coupled-electron pair approaches: An attempt to revive the pair natural orbital method
TL;DR: An efficient production level implementation of the closed shell CEPA and CPF methods is reported that can be applied to medium sized molecules and has essentially the same accuracy as parent CEPA (CPF) methods for thermochemistry, kinetics, weak interactions, and potential energy surfaces but is up to 500 times faster.
References
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Density‐functional thermochemistry. III. The role of exact exchange
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
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Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
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Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
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Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
TL;DR: In this paper, a detailed study of correlation effects in the oxygen atom was conducted, and it was shown that primitive basis sets of primitive Gaussian functions effectively and efficiently describe correlation effects.
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Density-functional approximation for the correlation energy of the inhomogeneous electron gas
TL;DR: Numerical results for atoms, positive ions, and surfaces are close to the exact correlation energies, with major improvements over the original LM approximation for the ions and surfaces.