SCSD · Semiclassical Spin Dynamics in Condensed Phase

Quantum mechanical, spin dynamic calculations for NMR purposes, rapidly becomes very complicated when the studied spin systems increase in size. In this project we aim to study methods in which semiclassical molecular dynamics are explored to tackle this problem. Methods for semiclassical approximations have since long times been established within the fields of radical chemistry and optical spectroscopy research but are little explored within the field of NMR. We intend to explore methods where in addition to a smaller completely quantum mechanically described spin systems are investigated, the complete (large) nuclear surrounding is included in a classical manner. More specifically we will add Hamiltonian terms of the Caldeira-Leggett type and eventually simulate the anharmonic environment with ab initio molecular dynamics or empirical force fields. The benefit of the proposed strategy is that matrix size increases linearly with the number of nuclei included instead of exponentially if the environment can be described classically. This will be done by a step by step project plan in which during the earlier work packages investigations of spin systems without the environment included is done. Then once, we have established suitable quantum dynamics methods, we will proceed to include the environment. If this succeeds and we manage to correctly calculate spin dynamics with the impact of the environment in terms of relaxation taken into account, we will continue to the later work packages and try to use this to aid NMR pulse design. If this is successful, this project will open doors to more efficient NMR simulations and provide quantum physical insights to NMR dynamics.