I want to calculate the angle between the transition electric dipole of the first electronic excitation of two molecules, A and B.
In order to do that, I've already performed TD-DFT calculations on both molecules, and extracted from the output the coordinates for both vectors. However, to calculate the angle, I need to know if the transition dipole vector coordinates are calculated and displayed with respect to the Cartesian coordinate center or with respect to the Center-of-Mass of each molecule.
Can someone please clarify this?