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511 results on '"Hättig, Christof"'

169. Accurate Nonlinear Optical Properties for Small Molecules.

Author

Papadopoulos, Manthos G., Sadlej, Andrzej J., Leszczynski, Jerzy, Christiansen, Ove, Coriani, Sonia, Gauss, Jürgen, Hättig, Christof, JØrgensen, Poul, Pawłowski, Filip, and Rizzo, Antonio

Abstract

During the last decade it became possible to calculate by quantum chemical ab initio methods not only static but also frequency-dependent properties with high accuracy. Today, the most important tools for such calculations are coupled cluster response methods in combination with systematic hierarchies of correlation consistent basis sets. Coupled cluster response methods combine a computationally efficient treatment of electron correlation with a qualitatively correct pole structure and frequency dispersion of the response functions. Both are improved systematically within a hierarchy of coupled cluster models. The present contribution reviews recent advances in the highly accurate calculation of frequency-dependent properties of atoms and small molecules, electronic structure methods, basis set convergence and extrapolation techniques. Reported applications include first and second hyperpolarizabilities, Faraday, Buckingham and Cotton-Mouton effects as well as Jones and magneto-electric birefringence [ABSTRACT FROM AUTHOR]

Published
2006
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178. Turbomole.

Author

Furche, Filipp, Ahlrichs, Reinhart, Hättig, Christof, Klopper, Wim, Sierka, Marek, and Weigend, Florian

Subjects
QUANTUM chemistry, COMPUTER systems, MOLECULES, DENSITY functional theory, LAPLACE transformation
Abstract

Turbomole is a highly optimized software package for large-scale quantum chemical simulations of molecules, clusters, and periodic solids. Turbomole uses Gaussian basis sets and specializes on predictive electronic structure methods with excellent cost to performance characteristics, such as (time-dependent) density functional theory ( TDDFT), second-order Møller- Plesset theory, and explicitly correlated coupled cluster ( CC) methods. These methods are combined with ultraefficient and numerically stable algorithms such as integral-direct and Laplace transform methods, resolution-of-the-identity, pair natural orbitals, fast multipole, and low-order scaling techniques. Apart from energies and structures, a variety of optical, electric, and magnetic properties are accessible from analytical energy derivatives for electronic ground and excited states. Recent additions include post- Kohn- Sham calculations within the random phase approximation, periodic calculations, spin-orbit couplings, explicitly correlated CC singles doubles and perturbative triples methods, CC singles doubles excitation energies, and nonadiabatic molecular dynamics simulations using TDDFT. A dedicated graphical user interface and a user support network are also available. [ABSTRACT FROM AUTHOR]

Published
2014
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