Excited state dynamics initiated by an electromagnetic field within the Variational Multi-Configurational Gaussian (vMCG) method

Abstract

The Variational Multi-Configurational Gaussian (vMCG) approach offers a framework to perform exact trajectory-based quantum dynamics. Herein we use two model vibronic coupling Hamiltonians of pyrazine to explore, for the first time, the influence of the coupling between the external field and the Gaussian basis functions (GBFs) in vMCG on the dynamics. We show that when the excitation pulse is short compared to the nuclear dynamics, vertical projection without a field and explicit description of the external field converge. For longer pulses, a sizeable change is observed. We demonstrate that comparatively few GBFs are sufficient to provide qualitative agreement to MCTDH dynamics and a quantitative agreement can be achieved using ∼100 GBFs. Longer pulses require more GBFs due to the prolonged coupling between the ground and excited states. Throughout the single set formalism offers the fastest convergence.

Simulation of ultrafast excited-state dynamics and elastic x-ray scattering by quantum wavepacket dynamics

“…The only notable difference is the damping of the fast 1 MLCT ↔ 3 MLCT oscillations for the 60 fs pulse. This is expected, 8,63 as the pulse duration approaches the period of the observed oscillations. These results also justify the utilization of impulsive excitation to the 1 MLCT states for the simulation of excited-state dynamics of [Fe(bmip) 2 ] 2+ .…”

The quantum-Ehrenfest method with the inclusion of an IR pulse: Application to electron dynamics of the allene radical cation

“…This implementation is straightforward in the Qu-Eh method due to the use of a single time-dependent potential energy surface. Other alternative methods of including an external electric field in dynamics can be accomplished by including the product of the field with the transition dipole moment in the equation of motion, 26,27 propagator for semi-classical dynamics, 28 a local-control method, 29 and a Floquet Hamiltonian. 30 A more detailed review can be found in the paper of Antipov…”

Relaxation dynamics through a conical intersection: Quantum and quantum–classical studies

“…Trajectory-based approaches to nonadiabatic dynamics are powerful tools for predicting the fate of a molecule after photo-excitation [1][2][3][4][5][6][7][8][9][10][11][12][13] or the products of a collision reaction [14][15][16][17] . The underlying approximations, in the treatment of nuclear dynamics 3,12,[18][19][20] and in the description of electron-nuclear coupling 12,[21][22][23][24][25] , make them computationally efficient, at least compared to a numerically-exact solution of the time-dependent Schr ödinger equation 19 .…”

“…Trajectory-based approaches to nonadiabatic dynamics are powerful tools for predicting the fate of a molecule after photo-excitation [1][2][3][4][5][6][7][8][9][10][11][12][13] or the products of a collision reaction [14][15][16][17] . The underlying approximations, in the treatment of nuclear dynamics 3,12,[18][19][20] and in the description of electron-nuclear coupling 12,[21][22][23][24][25] , make them computationally efficient, at least compared to a numerically-exact solution of the time-dependent Schr ödinger equation 19 . Clearly, the computational efficiency comes at the price of losing accuracy or missing critical features, such as tunnelling and zero-point energy [26][27][28][29][30] , interferences 31,32 , quantum decoherence [33][34][35][36] , to name some of the usual suspects.…”