Electronic structure methods are important tools used to understand, study and predict the behavior of molecular systems. Advancement of these methods is the main objective of this proposal. The applicability of accurate electron correlation methods is li mited by the steep increase in the computational cost when the size of the molecular system is increased.
We propose a new and different approach where the computational cost of electron correlation methods becomes constant with the size of the molecular system. This is obtained using multi-level methods where different levels of theory can be applied to different parts of the system. In this way we avoid calculating the total wave function and only the part relevant for a local molecular property is det ermined. We say the methods have size-intensive complexity.
The multi-level approach will be developed in many directions. For single molecules we will develop coupled cluster wave function and response methods, together with multi-configurational self-c onsistent field methods and for relativistic methods. For crystals we will develop multi-level methods at the unit cell level with periodic boundary conditions.
The developed methods will be used to simulate chiroptical properties of molecules and crysta ls. This will be done in collaboration with internationally recognized scientists that are highly experienced in simulating optical activity in different type of systems.