Rapid and accurate simulation of electron dynamics across nanostructures

Accurate first-principles modeling of electron dynamics is a challenging area of research. To follow the dynamics of molecular electron density one has to solve the time-dependent electronic Schrödinger equation (TDSE). Straight-forward extensions of common quantum chemistry methods to the time-dependent domain reveal density functional theory (DFT), or even the coupled cluster theories to be extremely unsuited for this purpose. In a series of studies, we have demonstrated linear equations of motions to be one of the fundamental requirements to reliably model electonic wavepacket dynamics, or coherent controlled state-to-state excitation. To this end, we have developed one of the most effcient implementations of the time-dependent configuration-interaction (TDCI) methodology to solve the TDSE. Our implementation has been successfully applied to follow the electron transport across molecular wires and nanostructures terminating in a small metal cluster or a model gold surface. When combined with imaginary time propagation, or other variational schemes TDCI can be utilized also to perform time-independent task of computing the bound states. The present talk will provide an overview of the TDCI methodology and summarize the results of some recent applications.

References
[1] Raghunathan, et al., Critical examination of explicitly time-dependent density functional theory for coherent control of dipole switching Journal of Chemical Theory and Computation, 7 (2011) 2492.
[2] Ulusoy, et al., The multi-configuration electron-nuclear dynamics method applied to LiH, The Journal of chemical physics, 136 (2012) 054112.
[3] Ramakrishnan, et al., Control and analysis of single-determinant electron dynamics,Physics Review A, 85 (2012) 054501.
[4] Ramakrishnan, et al., Electron dynamics across molecular wires: A time-dependent configuration interaction study, Chemical Physics, 420 (2013) 44.
[5] Ramakrishnan, et al., Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches, Chemical Physics, 446 (2015) 24.