Figure 30.

Simulations of EP → ZM → ZP half-cycle of MTDP. (A) Minimum energy path EP → ZP of the MTDP motor θ (the torsion angle defining the position of rotor with respect to stator) calculated with the SSR method (triangles). The dashed energy profiles correspond to 3-root state-average XMS-CASPT2 energies calculated with a 2 electrons in 2 π-orbitals complete active space. The dotted energy profiles show the corresponding 5-root state-average with a 10 electrons in 10 π-orbitals complete active space. (B) The top panel summarizes the conformational changes of MTDP in solvent along the QM/MM trajectories. The bottom panel shows the flexible part of the MTDP in methanol QM/MM model. (C) Simulated photoisomerization of MTDP in methanol solution based on 8 productive trajectories observed using 40 initial conditions with EP-helicity character. The propagation along the S₁ PES (the black lines) is connected with the reactive propagation along the S₀ PES (the red lines) by the corresponding hop points (the red circles). (D) Picosecond-scale simulation of MTDP photoisomerization in methanol solution as demonstrated through 8 reactive CCW trajectories. The top panel shows 4 trajectories in which EP to ZP transition occurs within 2.5 ps. The bottom panel demonstrated 2 trajectories in which EP to ZP transition occurs within 6 ps. The propagation along the S₁ PES is shown with solid black lines, while the propagation along S₀ is shown with solid red lines. The hop points are marked with red circles. The point of trajectory at which ZP conformer becomes stable is identified with vertical dashed black lines.