On the inclusion of the diagonal Born-Oppenheimer correction in surface hopping methods

The diagonal Born-Oppenheimer correction (DBOC) stems from the diagonal second derivative coupling term in the adiabatic representation, and it can have an arbitrary large magnitude when a gap between neighbouring Born-Oppenheimer (BO) potential energy surfaces (PESs) is closing. Nevertheless, DBOC...

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Bibliographic Details
Published in:The Journal of chemical physics 2016-04, Vol.144 (15), p.154103-154103
Main Authors: Gherib, Rami, Ye, Liyuan, Ryabinkin, Ilya G., Izmaylov, Artur F.
Format: Article
Language:English
Subjects:
BORN-OPPENHEIMER APPROXIMATION
Computer simulation
COUPLINGS
Electron states
EXPERIMENTAL DATA
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
Intersections
KINETIC ENERGY
Mathematical models
PHASE SPACE
Physics
POTENTIAL ENERGY
SIMULATION
SURFACES
Two dimensional models
TWO-DIMENSIONAL CALCULATIONS
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Summary:The diagonal Born-Oppenheimer correction (DBOC) stems from the diagonal second derivative coupling term in the adiabatic representation, and it can have an arbitrary large magnitude when a gap between neighbouring Born-Oppenheimer (BO) potential energy surfaces (PESs) is closing. Nevertheless, DBOC is typically neglected in mixed quantum-classical methods of simulating nonadiabatic dynamics (e.g., fewest-switch surface hopping (FSSH) method). A straightforward addition of DBOC to BO PESs in the FSSH method, FSSH+D, has been shown to lead to numerically much inferior results for models containing conical intersections. More sophisticated variation of the DBOC inclusion, phase-space surface-hopping (PSSH) was more successful than FSSH+D but on model problems without conical intersections. This work comprehensively assesses the role of DBOC in nonadiabatic dynamics of two electronic state problems and the performance of FSSH, FSSH+D, and PSSH methods in variety of one- and two-dimensional models. Our results show that the inclusion of DBOC can enhance the accuracy of surface hopping simulations when two conditions are simultaneously satisfied: (1) nuclei have kinetic energy lower than DBOC and (2) PESs are not strongly nonadiabatically coupled. The inclusion of DBOC is detrimental in situations where its energy scale becomes very high or even diverges, because in these regions PESs are also very strongly coupled. In this case, the true quantum formalism heavily relies on an interplay between diagonal and off-diagonal nonadiabatic couplings while surface hopping approaches treat diagonal terms as PESs and off-diagonal ones stochastically.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4945817