New strategies for non-adiabatic dynamics with trajectories
Date | Do, 11.07.2019 | |
Time | 16.45 | |
Speaker | Dr. Ivano Tavernelli, IBM, Zürich | |
Location | ETHZ Hönggerberg, HCI D 2 | |
Program | Among the most commonly used trajectory-based mixed quantum-classical schemes are Ehrenfest dynamics and Tully’s fewest switching surface hopping (FSSH). Despite their enormous impact in the quantum chemistry community, these methods suffer from many limitations e.g., the impossibility to describe wavepacket branching in Ehrenfest dynamics and the presence of over-coherence in FSSH. These failures are mainly associated to the approximate character of these approaches, which can hardly be improved due to the lack of a solid theoretical derivation. To overcome these limitations, several alternative trajectory-based methods have been developed, which all share the common feature of being derived from a well defined mixed quantumclassical limit of the underlying exact time-dependent Schrödinger equation. Among others, there are multiple spawning [1], Bohmian dynamics [2], exact factorization [3] and the conditional wavefunction approaches. In this talk, I present some novel and promising trajectory-based NAMD schemes derived from different rigorous mixed quantum-classical limits of the exact electron-nuclear quantum dynamics. In particular, I describe the derivation and the implementation of a trajectory-based solution of Bohmian dynamics and a mixed quantum-classical limit of the exact factorization theorem, which leads to a new trajectory-based non-adiabatic scheme [4, 5] (named coupled trajectory mixed quantum-classical dynamics, CT-MQCD) that can capture important nuclear quantum coherence/decoherence effects neglected in FSSH. The CT-MQCD approach and its single-trajectory limit are then applied to the study of the ultrafast electron and nuclear dynamics of photo-excited oxirane [4] and of ionized amino acids [6] in the gas phase. [1] M. Ben-Nun, J. Quenneville , and T. J. Martínez, J. Phys. Chem. A 104, 5161–5175 (2000). [2] B.F.E. Curchod, I. Tavernelli, J. Chem. Phys. 138, 184112 (2013); I. Tavernelli, Phys. Rev. A, 87, 042501 (2013). [3] A. Abedi, F. Agostini, E.K.U. Gross, Europhysics Letters 106, 33001 (2014). [4] S.K. Min, F. Agostini, I. Tavernelli, E. K. U. Gross, J. Phys. Chem. Lett., 8, 3048-3055 (2017). [5] F. Agostini, I. Tavernelli, G. Ciccotti, Eur. Phys. J., accepted, May 2018. [6] M. Lara-Astiaso, D. Ayuso, I. Tavernelli, P. Decleva, A. Palacios, F. Martin, Faraday discussions, 194, 41-59 (2016). |
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