Co-reporter:Daniel Peláez, Keyvan Sadri, Hans-Dieter Meyer
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 119() pp:42-51
Publication Date(Web):5 February 2014
DOI:10.1016/j.saa.2013.05.008
•Proton transfer in H3O2− characterized in agreement with experiment.•We have combined MCTDH with numerical KEO and newly developed MGPF.•Full (9D) and reduced (7D) dimensionality models are consistent.In this study, we present a full-dimensional (9D) quantum dynamical analysis of the lowest vibrational eigenstates of H3O2-. We have made use of the Multiconfiguration Time-Dependent Hartree method in conjunction with both an analytical and a numerical representation of the Kinetic Energy Operator and the newly developed Multigrid POTFIT [D. Peláez, H.-D. Meyer, J. Chem. Phys. 138 (2013) 014108], an algorithm which performs the transformation of a high-dimensional (up to ∼12D) Potential Energy tensor into product form. Many sets of top-down Multigrid POTFIT expansions, differing in the system coordinate definition (valence and Jacobi), as well as in the number of terms in the expansion, have been analyzed. Relaxations for the computation of the ground states energies have been carried out on these potentials, obtaining an excellent overall agreement with accurate previous Diffusion Monte Carlo (DMC) calculations, irrespective of the coordinate choice. The 24 lowest excited vibrational states of H3O2- have been computed by Block Relaxation and assigned for the first time. This has been carried out in two different pictures, namely: a 7D reduced dimensional one, in which the OH distances have been frozen at the Potential Energy Surface minimum, and a 9D full-dimensional one. The agreement between both descriptions is remarkable. The following fundamental modes have been characterized: OH torsion, OO stretching, OH wagging, OH rocking, and the elusive bridging H stretching. In particular, we provide a very accurate description of the latter in perfect agreement with experiment.
Co-reporter:R.F. Malenda, F. Gatti, H.-D. Meyer, D. Talbi, A.P. Hickman
Chemical Physics Letters 2013 Volume 585() pp:184-188
Publication Date(Web):14 October 2013
DOI:10.1016/j.cplett.2013.08.083
•Comparison of two different methods to treat rotationally inelastic scattering.•Excellent agreement obtained.•MCTDH and coupled channel calculations have complementary advantages and drawbacks.•MCTDH scales better as number of degrees of freedom increases.Calculations of rotationally inelastic scattering at thermal energies for a model atom–diatom system have been performed using two completely different methodologies. The first method is the multi-configuration time-dependent Hartree (MCTDH) wave packet method, and the second is the well known, time-independent, Arthurs and Dalgarno coupled channel formalism. Excellent agreement is obtained between the two calculations. The advantages and drawbacks of these two methods are somewhat complementary, so that the decision to use one or the other approach will depend on what type of computational results are desired.
Co-reporter:Matthis Eroms, Martin Jungen, and Hans-Dieter Meyer
The Journal of Physical Chemistry A 2012 Volume 116(Issue 46) pp:11140-11150
Publication Date(Web):July 5, 2012
DOI:10.1021/jp304666k
We present a theoretical investigation of the resonant Auger effect in gas-phase water. As in our earlier work, the simulation of nuclear dynamics is treated in a one-step picture, because excitation and decay events cannot be disentangled. Extending this framework, we now account for the vibronic coupling in the cationic final states arising from degeneracies in their potential energy surfaces (PESs). A diabatization of the cationic states permits a correct treatment of non Born–Oppenheimer dynamics leading to a significantly better agreement with experimental results. Moreover, we arrive at a more balanced understanding of the various spectral features that can be attributed to nuclear motion in the core-excited state or to vibronic coupling effects. The nuclear equations of motion have been solved using the multiconfiguration time-dependent Hartree (MCTDH) method. The cationic PESs were recalculated using the coupled electron pair approach (CEPA) whereas previously a multireference configuration interaction method had been employed.
Co-reporter:Oriol Vendrell Dr.;Fabien Gatti Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 2) pp:352-355
Publication Date(Web):
DOI:10.1002/anie.200804646
Co-reporter:Oriol Vendrell Dr.;Fabien Gatti Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 2) pp:358-361
Publication Date(Web):
DOI:10.1002/ange.200804646
Co-reporter:Michael R. Brill, Fabien Gatti, David Lauvergnat, Hans-Dieter Meyer
Chemical Physics 2007 Volume 338(2–3) pp:186-199
Publication Date(Web):25 September 2007
DOI:10.1016/j.chemphys.2007.04.002
Abstract
The nonadiabatic dynamics of ethene in its N, V and Z valence states is reinvestigated. Wave packet dynamics initiated by a vertical π → π∗ excitation is studied and particular emphasis is put on the investigation of the evolution of diabatic and adiabatic state populations. A new algorithm for computing the adiabatic state populations from diabatically represented wavefunctions is discussed and applied here for the first time. We have used the potential model of ethene which was derived by Krawczyk et al. [R.P. Krawczyk, A. Viel, U. Manthe, W. Domcke, Photoinduced dynamics of the valence states of ethene: a six-dimensional potential-energy surface of three electronic states with several conical intersections. J. Chem. Phys.119 (2003) 1397–1411] and the kinetic energy operator derived by Viel et al. [A. Viel, R.P. Krawczyk, U. Manthe, W. Domcke, Photoinduced dynamics of ethene in the N, V and Z valence states: a six-dimensional nonadiabatic quantum dynamics investigation, J. Chem. Phys.120 (2004) 11000–11010]. However, a second kinetic energy operator, which is more accurate than the first one, was derived and applied. The results of our calculations are in qualitative agreement with the previous ones of Viel et al., but there are marked quantitative differences.
Co-reporter:Oriol Vendrell Dr.;Fabien Gatti Dr. Dr.
Angewandte Chemie 2007 Volume 119(Issue 36) pp:
Publication Date(Web):3 AUG 2007
DOI:10.1002/ange.200702201
Die Kopplung macht's: Die Dynamik und das IR-Absorptionsspektrum des protonierten Wasser-Dimers werden durch volldimensionale quantenmechanische Rechnungen simuliert. Starke Kopplungen zwischen der IR-aktiven Protonentransfer-Bewegung und den niederfrequenten Kombinationsmoden werden identifiziert, und ihre Rolle in der Clusterdynamik wird erklärt. Diese Kopplungen sind für die charakteristische Dublett-Spitze um 1000 cm−1 verantwortlich.
Co-reporter:Oriol Vendrell Dr.;Fabien Gatti Dr. Dr.
Angewandte Chemie International Edition 2007 Volume 46(Issue 36) pp:
Publication Date(Web):3 AUG 2007
DOI:10.1002/anie.200702201
Coupling shakes this couple: Dynamics and the IR absorption spectrum of the protonated water dimer are reported by full-dimensional quantum simulation. Strong couplings between the IR-active proton-transfer motion and low-frequency, large-amplitude torsional modes are clearly identified, and their role in the cluster dynamics is explained. These couplings are responsible for the characteristic doublet at about 1000 cm−1.
Co-reporter:Daniel Peláez, Hans-Dieter Meyer
Chemical Physics (12 January 2017) Volume 482() pp:
Publication Date(Web):12 January 2017
DOI:10.1016/j.chemphys.2016.08.025
In this work, we present an MCTDH simulation of the infrared (IR) spectrum of the H3O2- cluster anion and compare it to the Ar vibrational predissociation experimental one. In particular, we have focused on the 600–1900cm-1 energy region, which is the lowest energy region experimentally accessible. The computed bands have been assigned to the corresponding eigenstates. The latter have been obtained through Block Improved Relaxation calculations. An overall very good agreement between theory and experiment is achieved. However, certain discrepancies between the calculated IR and the experimental Ar vibrational predissociation one exist. We provide evidence that they are due to the influence of the attached Ar atom.
