We devise an algorithm which, given a bounded automaton A, decides whether the group generated by A is finite. The solution comes from description of infinite sequences having A-orbit using deterministic finite-state acceptor. This acceptor can also be used to decide acts level-transitively.

Efficiencies of organic solar cells have practically doubled since the development non-fullerene acceptors (NFAs). However, generic chemical design rules for donor-NFA combinations are still needed. Such proposed by analyzing inhomogeneous electrostatic fields at donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and alignment parallel to interface, re...