OPLS4: improving force field accuracy on challenging regimes of chemical space - Lu, C; Wu, C; Ghoreishi, D; Chen, W; Wang, L; Damm, W; Ross, G A; Dahlgren, M K; Russell, E; Von Bargen, C D; Abel, R; Friesner, R A; Harder, E D (J Chem Theory Comput, 2021)