Influence of nuclear fluctuations on the NMR parameters of bullvalene: A Feynman path integral – Ab initio study

The isotropic magnetic shieldings and chemical shifts in bullvalene have been determined by Feynman path integral Monte Carlo simulations which have been combined with the gauge-including atomic orbital formalism. This setup renders possible the treatment of the quantum and thermal nuclear degrees of freedom in the calculation of NMR quantities. Ab initio Hartree–Fock Hamiltonians have been employed in the present ensemble averaging of NMR parameters. The vibrational motions cause a nuclear deshielding which depends on the topology of the centre studied. The consideration of these corrections leads to a better agreement between measured and calculated chemical shifts.