Circular dichroism (CD) is a widely used spectroscopy technique to detect chiral structures or molecules, such as proteins. We collaborate with Professor Yu Zhong's group to investigate the CD spectrum of a series of Cu Salen helical and linear polymers synthesized by his lab. My work focuses on the theoretical calculation of the electronic structures and making plots of CD spectrum from electric and magnetic dipole moment. Our theoretical work is an essential complement to their lab work, as experiment techniques are not able to unravel all features of this novel polymer chain, including their geometry, the relation between the handedness of the monomer and the helix, and the origin of the circular dichroism. The second part of this thesis dives into molecular dynamics simulations to develop a framework to implement constraints on specific atom motions in the context of on-the-fly semiclassical simulations. We first use PySCES, a Python code developed by our group, to test our constrained dynamics on a benzene molecule. Then we apply this method to the simulation of fluorescence anisotropy of 1,2'-bipentacene, where there is a difference between the polarization of incident light, which is used to excite molecules, and fluorescence light as a function of time.