The development of low-order scaling fully relativistic wave function methods and their application to organic light-emitting diodes
Final Report Abstract
In this project a formulation of relativistic two-component (2C) and multi-reference second-order perturbation theory methods in the atomic and active molecular orbital basis was established to pave the way for calculations on large heavy element-containing and open-shell molecules. The Laplace-transformed atomic orbital-based formulation of 2C second-order Møller–Plesset perturbation theory (MP2) is computationally beneficial as the number of additional spin-orbit (SO) terms is much smaller than in conventional spinor-based approaches. Most of these SO contributions are small in magnitude and are neglected in a production-level implementation. Since, in practise, one often deals with molecules that are composed of only a very few heavy – but mainly light – elements, such an approach becomes particularly useful. Furthermore, it was shown that the Laplace transformation of denominators is also applicable to the partially contracted variant of n-electron valence second-order perturbation theory (PC-NEVPT2). Some of the eight different contributions to the NEVPT2 correlation energy feature very small denominator ranges and for those only a very small number of quadrature points is required to reach a target accuracy, which is computationally desirable.
Publications
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Improvements on the minimax algorithm for the Laplace transformation of orbital energy denominators. J. Comput. Phys., 2016, 321, 927–931
Helmich-Paris, B. and Visscher, L.
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Laplace–transformed atomic orbital-based Møller–Plesset perturbation theory for relativistic two-component Hamiltonians. J. Chem. Phys., 2016, 145
Helmich-Paris, B.; Repisky, M.; and Visscher, L.
