title: Exact two-component relativistic theory for nuclear magnetic resonance parameters.
abstract: An exact two-component (X2C) relativistic theory for nuclear magnetic resonance parameters is obtained by first a single block-diagonalization of the matrix representation of the Dirac operator in a magnetic-field-dependent basis and then a magnetic perturbation expansion of the resultant two-component Hamiltonian and transformation matrices. Such a matrix formulation is not only simple but also general in the sense that the various ways of incorporating the field dependence can be treated in a unified manner. The X2C dia- and paramagnetic terms agree individually with the corresponding four-component ones up to machine accuracy for any basis.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, and Center for Computational Science and Engineering, Peking University, People's Republic of China.
authors.forename: Qiming
authors.initials: Q
authors.lastname: Sun
authors.forename: Wenjian
authors.initials: W
authors.lastname: Liu
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Xiao
authors.forename: Lan
authors.initials: L
authors.lastname: Cheng