Algorithmic decoherence time for decay-of-mixing non-Born-Oppenheimer dynamics

Shu Chun Cheng, Chaoyuan Zhu, Kuo Kan Liang, Sheng Hsien Lin, Donald G Truhlar

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


The performance of an analytical expression for algorithmic decoherence time is investigated for non-Born-Oppenheimer molecular dynamics. There are two terms in the function that represents the dependence of the decoherence time on the system parameters; one represents decoherence due to the quantum time-energy uncertainty principle and the other represents a back reaction from the decoherent force on the classical trajectory. We particularly examine the question of whether the first term should dominate. Five one-dimensional two-state model systems that represent limits of multidimensional nonadiabatic dynamics are designed for testing mixed quantum-classical methods and for comparing semiclassical calculations with exact quantum calculations. Simulations are carried out with the semiclassical Ehrenfest method (SE), Tully's fewest switch version (TFS) of the trajectory surface hopping method, and the decay-of-mixing method with natural switching, coherent switching (CSDM), and coherent switching with reinitiation (CSDM-D). The CSDM method is demonstrated to be the most accurate method, and it has several desirable features: (i) It behaves like the representation-independent SE method in the strong nonadiabatic coupling regions; (ii) it behaves physically like the TFS method in noninteractive region; and (iii) the trajectories are continuous with continuous momenta. The CSDM method is also demonstrated to balance coherence well with decoherence, and the results are nearly independent of whether one uses the adiabatic or diabatic representation. The present results provide new insight into the formulation of a physically correct decoherence time to be used with the CSDM method for non-Born-Oppenheimer molecular dynamic simulations.

Original languageEnglish (US)
Article number024112
JournalJournal of Chemical Physics
Issue number2
StatePublished - 2008

Bibliographical note

Funding Information:
This work is supported by National Science Council of the Republic of China under Grant No. 96-2113-M-009-021 and by the National Science Foundation under Grant No. CHE07-04974. C.Z. would like to thank the MOE-ATU project of the National Chiao Tung University for the support.


Dive into the research topics of 'Algorithmic decoherence time for decay-of-mixing non-Born-Oppenheimer dynamics'. Together they form a unique fingerprint.

Cite this