The QUILD (Quantum-regions Interconnected by Local Description) program has been developed for enabling calculations through multi-level approaches, in which different computational treatments are used for different regions of the system under study, see the separate Quild manual.

Hybrid Engine (QM/MM, QM/QM’)

The Hybrid engine is meant for mechanical or electrostatic embedding and QM/MM (QM/QM’) calculations that combine multiple engines. Some of the functionality of QUILD can be achieved using the Hybrid engine. See the separate Hybrid Engine manual.