We develop novel theoretical and computational methods to obtain detailed understanding of quantum dynamics involving changes in spin, energy and charge states in organic photovoltaics, at metallic and semiconductor surfaces, and in bio-molecules. Quantum processes in these systems constitute crucial steps in many areas of fundamental and technological importance: solar energy conversion, UV-light DNA damage, magnetic field sensitivity in living species, catalysis at surfaces, and general surface chemistry. Due to exponential complexity of quantum mechanics, straightforward solution of the Schrödinger equation is impossible for extended systems of our interest. In many cases though, the system can be split into a subsystem where quantum effects are mainly encapsulated and an environment which profoundly affects the subsystem behavior but whose dynamics can be treated with computationally less expensive methods. In our developments, we pursue two main avenues based on the subsystem-environment splitting: hybrid and renormalization approaches. In the hybrid scheme different levels of theory are employed for different parts of the system, for example, quantum mechanics for the subsystem and classical mechanics/electrodynamics for the environment. The renormalization scheme searches for dynamical equations which would include only subsystem degrees of freedom interacting through modified (renormalized) laws to account for the presence of the environment.