Global Optimization\nof a Spin-Crossover Molecule on\nMonolayer MoS<sub>2</sub>: Spin Transition-Induced Band Edge Shift

We investigate the interaction between\na Fe(II) spin-crossover\nmolecule and a two-dimensional (2D) substrate. Using density functional\ntheory combined with molecular dynamics simulations, we explore the\nconfiguration space and spin state energetics of the [Fe(py)<sub>2</sub>bpym(NCS)<sub>2</sub>] molecule adsorbed on the 2D semiconductor\nMoS<sub>2</sub>. We show that the deposited molecule can display a\nhigh-spin ground state, in contrast to the locking of a low-spin state\nobserved on metallic substrates. The variation can be primarily attributed\nto the noncovalent interactions occurring at the interface. Furthermore,\nthe molecular doping of the n-type is examined from an electronic\nstructure point of view. Specifically, our calculations reveal a notable\nshift of the band edge that can reach 0.3 eV due to fluctuations in\nthe electric dipole at the interface upon spin-state switching. This\nobservation indicates the possibility of regulating the photocatalytic\nselectivity of hydrogen evolution and CO<sub>2</sub> reduction reactions\nwithin the heterostructure by manipulating the molecular spin state\nusing an external trigger.