After graduating, Schulten joined the Max Planck Institute for Biophysical Chemistry in Göttingen, where he remained till 1980. At the institute, he worked with Albert Weller on electron transfer reactions.  One of his first projects was to explain a chemical reaction product called a "fast triplet", an excited molecule with a pair of electrons with parallel spins.  What Schulten discovered was that a magnetic field could provably influence a chemical reaction, a physical effect that had not previously been demonstrated. It was possible to show the effect by causing the reaction to occur with and without a magnetic field. Schulten was particularly interested in implications of the magnetic field effect for biological systems such as electron transfer in photosynthesis.
Schulten also began to explore the possibility that fast triplets could explain compass sensors in biological species such as migrating birds. That the European robin used some form of magnetoreception was demonstrated by Wolfgang Wiltschko and Fritz Merkel in 1965, and further studied by Wolfgang and Roswitha Wiltschko. Schulten proposed that quantum entanglement of a radical-pair system could underlie a biochemical compass. Schulten and others have since extended this early work, developing a model of  the possible excitation of cryptochrome proteins in photoreceptors within the retina of the eye.