Hyperion: A New Computational Tool for Relativistic Ab Initio Hyperfine Coupling

Abstract

Herein we describe Hyperion , a new program for computing relativistic picture-change-corrected magnetic resonance parameters from scalar relativistic active space wave functions, with or without spin–orbit coupling (SOC) included a posteriori . Hyperion also includes a new orbital decomposition method for assisting active space selection for calculations of hyperfine coupling. For benchmarking purposes, we determine hyperfine coupling constants of selected alkali metal, transition metal, and lanthanide atoms, based on complete active space self-consistent field spin–orbit calculations in OpenMolcas. Our results are in excellent agreement with experimental data from atomic spectroscopy as well as theoretical predictions from four-component relativistic calculations.

The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

“…Alternatively, a similar method for calculation of relativistic HFC parameters based on the X2C transformation has also been implemented in the package, which interfaces with . , Similarly to ref , calculates X2C hyperfine coupling parameters on the basis of CAS/RAS/DMRG wave functions with or without RASSI-SO, and has been benchmarked against selected alkali metal, transition metal, and lanthanide atoms, showing excellent agreement with experimental data from atomic spectroscopy. includes an orbital decomposition method for assisting active space selection for calculations of HFC.…”

Perspective: Simultaneous treatment of relativity, correlation, and QED

“…In particular, the relationships between one‐ and multiple‐step X2C's have been made crystal clear 5 : They share the same decoupling condition and differ only in the renormalization, and can all be formulated either at matrix or operator level. Due to its simplicity, accuracy, and efficiency, 9,10,33–36 the one‐step X2C 28,29 has become the workhorse of relativistic quantum chemical calculations under the NPA, as symbolized by its realization in a large number of software packages 37–53 . Note that the Q term () can also be included in the transformation, so as to obtain eQED@X2C.…”

“…Due to its simplicity, accuracy, and efficiency, 9,10,[33][34][35][36] the one-step X2C 28,29 has become the workhorse of relativistic quantum chemical calculations under the NPA, as symbolized by its realization in a large number of software packages. [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Note that the Q term (10) can also be included in the transformation, so as to obtain eQED@X2C. Albeit defined only algebraically, the X2C Hamiltonian can still be separated into a spin-free part and a spindependent part by means of matrix perturbation theory, [54][55][56] namely,…”

“Relativity + Correlation + QED = Experiment”

“…Due to its simplicity, accuracy, and efficiency, [28][29][30][31][32][33] the one-step X2C 20,21 has become the workhorse of relativistic quantum chemical calculations under the NPA, as symbolized by its realization in a large number of software packages. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] Note that the Q term (10) can also be included in the transformation, so as to obtain eQED@X2C.…”