A quantum chemical perspective of photoactivated biological functions

Abstract Quantum chemistry plays a fundamental role in unraveling the mechanisms by which biological systems sense and use light, driving functions such as light harvesting and energy conversion, and photoreception and signaling. In this Perspective, we first present the fundamental physical principles underlying the light-induced biological functions. We then focus on the key theoretical frameworks and multiscale modeling strategies based on quantum chemistry that enable a detailed, atomistic description of the processes initiating the biological response to light. Special emphasis is placed on three fundamental photophysical and photochemical processes (excitation energy transfer, photochemical reactions, and electron transfer) which form the core of photoactivation mechanisms in biological systems. By highlighting the advances and challenges associated with the quantum chemical modeling, we demonstrate its essential contribution to deepening our understanding of photoinduced biological function and point to future directions for methodological innovation.