Journal ArticleDOI
Implementation of RI-CC2 triplet excitation energies with an application to trans-azobenzene
Christof Hättig,Kasper Hald +1 more
TLDR
In this paper, the triplet and triplet vertical excitation energies of trans-azobenzene were investigated using an explicitly spin coupled basis and the resolution of the identity approximation for two-electron integrals.Abstract:
Triplet excitation energies within the approximate coupled cluster singles and doubles model CC2 have been implemented using an explicitly spin coupled basis and the resolution of the identity approximation for two-electron integrals. This approach reduces substantially the requirements for CPU time, disk space and memory, and extends the applicability of CC2 for triplet excited states to molecules that could not be studied before with this method. We report an application to the lowest singlet and triplet vertical excitation energies of trans-azobenzene. An accurate ab initio geometry optimized at the MP2/cc-pVTZ level is presented, and CC2 calculations in the aug-cc-pVTZ basis set with 874 basis functions are combined with coupled cluster singles and doubles (CCSD) calculations in modest basis sets to obtain the best possible estimates for the vertical excitation energies. The results show that recently reported SOPPA calculations are unreliable.
Good agreement with experiment is obtained for the lowest excited singlet state S1, but for the lowest triplet state T1 the results indicate a large difference between the vertical excitation energy and the experimentally observed transition.read more
Citations
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Journal ArticleDOI
Equation-of-Motion Coupled-Cluster Methods for Open-Shell and Electronically Excited Species: The Hitchhiker's Guide to Fock Space
TL;DR: This review provides a guide to established EOM methods illustrated by examples that demonstrate the types of target states currently accessible by EOM, and touches on some formal aspects of the theory and important current developments.
Journal ArticleDOI
Recent advances in wave function-based methods of molecular-property calculations.
TL;DR: Recent Advances in Wave Function-Based Methods of Molecular-Property Calculations Trygve Helgaker, Poul Jørgensen, Kasper Kristensen, Jeppe Olsen, and Kenneth Ruud.
Journal ArticleDOI
TURBOMOLE: Modular program suite for ab initio quantum-chemical and condensed-matter simulations
Sree Ganesh Balasubramani,Guo P. Chen,Sonia Coriani,Michael Diedenhofen,Marius S. Frank,Yannick J. Franzke,Filipp Furche,Robin Grotjahn,Michael E. Harding,Christof Hättig,Arnim Hellweg,Benjamin Helmich-Paris,Christof Holzer,Uwe Huniar,Martin Kaupp,Alireza Marefat Khah,Sarah Karbalaei Khani,Thomas Müller,Fabian Mack,Brian Nguyen,Shane M. Parker,Eva Perlt,Dmitrij Rappoport,Kevin Reiter,Saswata Roy,Matthias Rückert,Gunnar Schmitz,Marek Sierka,Enrico Tapavicza,David P. Tew,Christoph van Wüllen,Vamsee K. Voora,Florian Weigend,Artur Wodyński,Jason M. Yu +34 more
TL;DR: This review focuses on recent additions to TURBOMOLE’s functionality, including excited-state methods, RPA and Green's function methods, relativistic approaches, high-order molecular properties, solvation effects, and periodic systems.
Journal ArticleDOI
The algebraic diagrammatic construction scheme for the polarization propagator for the calculation of excited states
Andreas Dreuw,Michael Wormit +1 more
TL;DR: The algebraic diagrammatic construction (ADC) scheme for the polarization propagator provides a series of ab initio methods for the calculation of excited states based on perturbation theory.
Journal ArticleDOI
Geometry optimizations with the coupled-cluster model CC2 using the resolution-of-the-identity approximation
TL;DR: In this article, an implementation of the gradient for the second-order coupled-cluster singles-and-doubles model CC2 is reported, which employs the resolution-of-the-identity (RI) approximation for electron repulsion integrals.
References
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Journal ArticleDOI
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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Efficient use of the correlation consistent basis sets in resolution of the identity MP2 calculations
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Journal ArticleDOI
The second-order approximate coupled cluster singles and doubles model CC2
TL;DR: In this article, an approximate coupled cluster singles and doubles model is presented, denoted CC2, where the total energy is of second-order Moller-Plesset perturbation theory (MP2) quality.