TY - JOUR

T1 - Indirect nuclear spin-spin couplings with third order contributions added to the SOPPA method

AU - Sanz Rodrigo, Javier

AU - Hillers-Bendtsen, Andreas Erbs

AU - Kjeldal, Frederik Ørsted

AU - Høyer, Nicolai Machholdt

AU - Mikkelsen, Kurt Valentin

AU - Sauer, Stephan P. A.

PY - 2023/3/28

Y1 - 2023/3/28

N2 - In this article, a modification of the second order polarization propagator approximation (SOPPA) method is introduced and illustrated for the calculation of the indirect nuclear spin-spin couplings. The standard SOPPA method, although cheaper in terms of computational cost, offers less accurate results than the ones obtained with coupled cluster methods. A new method, named SOPPA+A3-3, was therefore developed by adding the terms of the third order A matrix that rely on the second order double amplitudes. The performance of this third order contribution was studied using the CCSD method as a reference, calculating the spin-spin couplings of molecules of diverse sizes and compositions, and comparing them to the SOPPA method. The results show that inclusion of this third order contribution gives more accurate results than the standard SOPPA method with a level of accuracy close to that of the coupled cluster method with only small increase of computational cost of the response calculation that dominates the computational cost for small to medium sized molecules. The implementation of the first contributions to the third order polarization propagator approximation (TOPPA) in the Dalton program thus already shows a significant change in these molecular properties over those obtained with the standard SOPPA method.

AB - In this article, a modification of the second order polarization propagator approximation (SOPPA) method is introduced and illustrated for the calculation of the indirect nuclear spin-spin couplings. The standard SOPPA method, although cheaper in terms of computational cost, offers less accurate results than the ones obtained with coupled cluster methods. A new method, named SOPPA+A3-3, was therefore developed by adding the terms of the third order A matrix that rely on the second order double amplitudes. The performance of this third order contribution was studied using the CCSD method as a reference, calculating the spin-spin couplings of molecules of diverse sizes and compositions, and comparing them to the SOPPA method. The results show that inclusion of this third order contribution gives more accurate results than the standard SOPPA method with a level of accuracy close to that of the coupled cluster method with only small increase of computational cost of the response calculation that dominates the computational cost for small to medium sized molecules. The implementation of the first contributions to the third order polarization propagator approximation (TOPPA) in the Dalton program thus already shows a significant change in these molecular properties over those obtained with the standard SOPPA method.

U2 - 10.1063/5.0140117

DO - 10.1063/5.0140117

M3 - Journal article

C2 - 37003784

VL - 158

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

SN - 0021-9606

IS - 12

M1 - 124118

ER -