Relativistic Electronic Structure Theory for Molecular Spectroscopy

Abstract

This review provides a concise introduction to relativistic electronic structure theory with a focus on the prediction of parameters relevant for molecular spectroscopy. For this purpose, a brief overview of wave‐function‐based electronic structure methods with a special focus on the calculation of electron correlation effects is given. These are essential for an accurate prediction of spectroscopic parameters from first‐principles calculations. Then approximate relativistic Hamiltonians are discussed in detail regarding their accuracy and range of application. The a posteriori calculation of spin–orbit effects from correlated wave functions is briefly described and reviewed. The presentation concludes with an extensive discussion of calculated results for prototypical molecules. The focus is mainly on small molecules to which highly accurate relativistic methods can be applied and close agreement with experimental data can be achieved.

An efficient implementation of two-component relativistic exact-decoupling methods for large molecules

“…( 42) using Eq. (8). One can further reduce the computational cost by invoking the non-relativistic approximation (setting atomic decoupling transformation matrices to identity matrices) to all light atoms such as hydrogen [70].…”

“…Relativistic quantum chemistry is essential to the proper understanding of the chemistry of any element in the periodic table with high accuracy [1][2][3][4][5][6][7][8][9][10][11]. Especially in heavy and superheavy elements and their compounds, relativistic effects largely determine to their electronic structures, properties and functions.…”

Nuclear size effects in rotational spectra: A tale with a twist

“…P t 0in PtSi results obtained with the Douglas-Kroll-Hess Hamiltonian are available[94]. At the DKH(2,0) level, that is, using a 2nd order DKH Hamiltonian for the generation of orbitals and a 0th order (untransformed) property operator, we get picture change errors on the same order as above, whereas at the DKH(8,8) level the deviation with respect to the reference B3LYP/ 4 DC value is within 3 %.The effect of the basis set can be seen from the HF/ 4 DC results obtained for ρ , we see that adding tight 2s1p functions increases the value by 1.4 %, whereas going to the QZ+2s1p level has only a minor effect.…”