Energy Absorption and Storage in a Hamiltonian System in Partial Contact with a Heat Bath

To understand the mechanism allowing for long-term storage of excess energy in proteins, we study a Hamiltonian system consisting of several coupled pendula in partial contact with a heat bath. It is found that energy absorption and storage are possible when the motion of each pendulum switches between oscillatory (vibrational) and rotational modes. The relevance of our mechanism to protein motors is discussed.