Extension of the Lego-brick approach to protonated molecules

We take the opportunity to extend the applicability of the Lego-brick approach (that is, templating molecular systems from small fragments), by applying it to characterize structural properties of protonated molecules. We additionally present a new variant for it (LETSGO): instead of employing semi-experimental equilibrium geometries of fragments in the templating procedure, experimentally available structures are used. By comparison with experiment (rotational constants), we evaluate the performance of Lego-brick and LETSGO models on a significant range of systems. Our results appear to be a promising extension to techniques for generating equilibrium structures of protonated molecules. • The Lego-brick approach has been applied to protonated species. • LETSGO: a new variant of the Lego-brick approach has been introduced and tested. • Lego-brick / LETSGO reproduce rotational constants with an accuracy of 0.1% / 0.3%.