Showing papers by "Christof Hättig published in 2014"
Vilnius University1, University of Ferrara2, Aarhus University3, University of Oslo4, Royal Institute of Technology5, Electromagnetic Geoservices6, University of Trieste7, Norwegian Computing Center8, University of Southern Denmark9, University of Santiago de Compostela10, Danske Bank11, Ruhr University Bochum12, Norwegian Meteorological Institute13, Norwegian Defence Research Establishment14, University of Auckland15, Norwegian University of Science and Technology16, Information Technology University17, Technical University of Ostrava18, Linköping University19, Karlsruhe Institute of Technology20, ETH Zurich21, Australian National University22, University of Modena and Reggio Emilia23, Cisco Systems, Inc.24, University of Buenos Aires25, University of Copenhagen26, University of Erlangen-Nuremberg27, Kazimierz Wielki University in Bydgoszcz28, National Scientific and Technical Research Council29, University of Valencia30, Paul Sabatier University31, University of Melbourne32, University of Nottingham33, University of Bristol34, CLC bio35, Princeton University36, La Trobe University37, Clemson University38
TL;DR: Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory.
Abstract: Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, confi ...
1,212 citations
TL;DR: The current progress on the combination of explicit electron correlation with the pair natural orbital (PNO) representation is presented, and for the first time explicitly correlated CCSD results for the whole set and improved estimates for the C CSD/CBS limits are reported.
Abstract: We present our current progress on the combination of explicit electron correlation with the pair natural orbital (PNO) representation. In particular we show cubic scaling PNO-MP2-F12, and PNO-CCSD[F12] implementations. The PNOs are constructed using a hybrid scheme, where the PNOs are generated in a truncated doubles space, spanned by orbital specific virtuals obtained using an iterative eigenvector algorithm. We demonstrate the performance of our implementation through calculations on a series of glycine chains. The accuracy of the local approximations is assessed using the S66 benchmark set, and we report for the first time explicitly correlated CCSD results for the whole set and improved estimates for the CCSD/CBS limits. For several dimers the PNO-CCSD[F12] calculations are more accurate than the current reference values. Additionally, we present pilot applications of our PNO-CCSD[F12] code to host–guest interactions in a cluster model for zeolite H-ZSM-5 and in a calix[4]arene–water complex.
90 citations
TL;DR: In this paper, the authors studied the performance of a pair natural orbital (PNO) expansion for the description of partially or dominantly doubly excited states within a response theory framework.
52 citations
TL;DR: Palladium(II) complexes of bidentate cycloimidate ligand systems with a triarylmethyl moiety exhibit exceptional downfield shifts in proton NMR spectra due to rare anagostic interactions.
26 citations
TL;DR: This work investigates the performance of the approximate coupled cluster singles- and doubles model CC2 in the prediction of optical rotations of organic molecules and the influence of the molecular geometry and the one-electron basis set and tested to which extent spin-component scaling changes the results.
Abstract: We investigate the performance of the approximate coupled cluster singles- and doubles model CC2 in the prediction of optical rotations of organic molecules. For this purpose we employ a combination of two test sets from the literature which include small and medium-sized rigid organic molecules and a series of helicenes. CC2 calculations on molecules as large as 11-helicene became possible through a recent implementation of frequency-dependent second-order properties for CC2 which makes use of the resolution-of-the-identity approximation for the electron repulsion integrals. The results are assessed with respect to the accuracy of the absolute values of the optical rotation and the prediction of the correct sign, which is crucial for the determination of absolute configurations. The performance of CC2 is compared with that of density functional theory at the B3LYP and CAM-B3LYP levels. Furthermore we investigated the influence of the molecular geometry and the one-electron basis set and tested to which extent spin-component scaling changes the results.
14 citations
TL;DR: Scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model and Møller-Plesset perturbation theory with and without a spin-component scaling (SCS or spin-opposite scaling (SOS).
Abstract: We present scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model (CC2) and Moller-Plesset perturbation theory (MP2) with and without a spin-component scaling (SCS or spin-opposite scaling (SOS)). Frequency scaling factors and the remaining deviations from the reference data are evaluated for several non-augmented basis sets of the cc-pVXZ family of generally contracted correlation-consistent basis sets as well as for the segmented contracted TZVPP basis. We find that the SCS and SOS variants of CC2 and MP2 lead to a slightly better accuracy for the scaled vibrational frequencies. The determined frequency scaling factors can also be used for vibrational frequencies calculated for excited states through response theory with CC2 and the algebraic diagrammatic construction through second order and their spin-component scaled variants.
13 citations
TL;DR: In this article, the noncovalent interaction of the formic acid dimer (FAD) with pyrene and single-walled carbon nanotubes (SWCNTs) was studied using both density functional theory with an empirical dispersion correction as well spin-component-scaled and F12 variants of second-order Moller-Plesset perturbation theory.
Abstract: The noncovalent interaction of the formic acid dimer (FAD) with pyrene and single-walled carbon nanotubes (SWCNTs) is studied using both density functional theory with an empirical dispersion correction as well spin-component-scaled and F12 variants of second-order Moller–Plesset perturbation theory. For the FAD–pyrene model system, it is shown that the dispersion-corrected DFT methods provide similar accurate results for the noncovalent interaction of carboxylic acid dimers with large conjugated π-systems such as MP2 and SCS-MP2. The binding energy of FAD in SWCNTs is found to be sensitive to the radius of the nanotube. It amounts to ca. 22 kcal/mol in the armchair (6,6) SWCNT and decreases with increasing tube radius. In the armchair (8,8) SWCNT, the binding energy is already 25% smaller. To facilitate an experimental identification of FAD inside SWCNTs, we report results for the shifts of the vibrational frequency, where we could identify intense C–O, C═O and O–H stretch modes as promising infrared sig...
7 citations