The general focus of this project is to examine the response of a large molecular system to external, time-dependent driving.
Normal Mode Analysis without the Hessian
Very mild driving by a harmonic driving term of the form
where rij are internuclear distances and λij are coupling constants can be used to obtain the normal mode frequencies and modes of the molecular system. The normal mode frequencies are obtained sweeping the frequency ω, like in a CW experiment, and monitoring energy absorption. This approach avoids the calculation and diagonalization of the Hessian matrix, which can become impractical for very large molecular systems.
Pulsed driving of the dipole
Here the driving is of the form where is the dipole moment of the molecule and is the external electric field is of short duration and given by
This type of driving is used to simulate 2D IR experiments.
Refs. Alex Brown, Xiubin Zhang, and Joel M. Bowman, J. Chem. Phys.
Martina Kaledin, Alexey L. Kaledin, Alex Brown, and Joel M. Bowman, J. Chem. Phys.; Martina Kaledin, Alexey L. Kaledin, Alex Brown, and Joel M. Bowman, in