Details of Grant 

EPSRC Reference:	EP/R014493/1
Title:	A unified framework for quantum chemistry beyond the Born-Oppenheimer approximation
Principal Investigator:	Manby, Professor FR
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Chemistry
Organisation:	University of Bristol
Scheme:	Standard Research
Starts:	01 May 2018	Ends:	08 April 2022	Value (£):	345,241
EPSRC Research Topic Classifications:	Physical Organic Chemistry
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:	EP/R014183/1
Panel History:	Panel Date Panel Name Outcome 25 Oct 2017 EPSRC Physical Sciences - October 2017 Announced
Summary on Grant Application Form
In quantum chemistry the approximate formulations of quantum mechanics are applied to the behaviour of atoms, molecules, surfaces and reactions. The field is dominated by a small number of key approximations. The Born-Oppenheimer approximation, in which a separation is made between the motion of electrons and nuclei, has particular importance because it provides not only a powerful framework for modelling and simulation tools, but also the central theoretical foundation on which our understanding of molecular structure is based. However,the Born-Oppenheimer approximation breaks down in several important chemically, physically and technologically relevant contexts: key examples include practically all photo-activated processes, electrochemical reactions, transport of charge and energy, and chemical reactions where hydrogen atoms migrate. For this reason there is a huge research activity in nonadiabatic dynamics, aimed at moving beyond the Born-Oppenheimer approximation. Much of this work addresses the complexities arising from the introduction of the potential energy surface, whose introduction changes the problem from one where the Hamiltonian is a sum of one- and two-particle terms, to a Hamiltonian in which all nuclear degrees of freedom are coupled together. Here we propose to move beyond the Born-Oppenheimer approximation without introducing potential energy surfaces. The central idea of this proposal is to develop the quantum chemistry of coupled electronic-vibrational degrees of freedom, culminating in the development of time-dependent and linear-response coupled-cluster theories that capture the key effects in nonadiabatic processes. Representing the nonadiabatic dynamics whilst simultaneously describing the electronic structure at a coupled-cluster level of theory would herald a new era in the modelling of such processes, and we will perform challenging preliminary applications in photochemistry and prediction of vibronic spectra to illustrate the potential of the method.
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Organisation Website:	http://www.bris.ac.uk