QM/MM Optimisation with Quantum Coupling: Host-guest interactions in a pentacene-doped p-terphenyl crystal

BERTONI, ANDRÉS I.; FOGARTY, RICHARD M.; SÁNCHEZ, CRISTIAN G.; HORSFIELD, ANDREW P.

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2022 vol. 156 p. 44110 - 44110

0021-9606

In this work we present a novel force-based scheme to perform hybrid QM/MM computations. The proposed scheme becomes especially relevant for the simulation of host-guest molecular systems, where the description of the explicit electronic interactions between a guest molecule and a classically described host is of key importance. To illustrate its advantages, we utilise the presented scheme in the geometry optimisation of a technologically important host-guest molecular system: a pentacene-doped p-terphenyl crystal, a core component of a room-temperature MASER device. We show that, as opposed to the simpler and widely used hybrid scheme ONIOM, our Quantum-Coupling QM/MM (QC-QM/MM) scheme was able to reproduce explicit interactions in the minimum energy configuration for the host-guest complex. We also show that, as a result of these explicit interactions, the host-guest complex exhibits an oriented net electric dipole moment that is responsible for red-shifting the energy of the first singlet-singlet electronic excitation of pentacene.