Exploring Alternate Methods to High-Level Vibrational Correction Calculations of NMR Spin-Spin Coupling Constants
Publikation: Working paper › Preprint › Forskning
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Exploring Alternate Methods to High-Level Vibrational Correction Calculations of NMR Spin-Spin Coupling Constants. / Gleeson, Ronan; Aggelund, Patrick Alexander; Østergaard, Frederik Cornelius; Schaltz, Kasper Frølund; Sauer, Stephan P. A.
2023. s. 43.Publikation: Working paper › Preprint › Forskning
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TY - UNPB
T1 - Exploring Alternate Methods to High-Level Vibrational Correction Calculations of NMR Spin-Spin Coupling Constants
AU - Gleeson, Ronan
AU - Aggelund, Patrick Alexander
AU - Østergaard, Frederik Cornelius
AU - Schaltz, Kasper Frølund
AU - Sauer, Stephan P. A.
PY - 2023/11/2
Y1 - 2023/11/2
N2 - Traditional nuclear magnetic resonance (NMR) calculations typically treat systems with a Born-Op penheimer-derived electronic wavefunction that is solved for a fixed nuclear geometry. One can numerically account for this neglected nuclear motion by averaging over property values for all nuclear geometries with a vibrational wavefunction and adding this expectation value as a correction to an equilibrium property value. Presented are benchmark coupled-cluster singles and doubles (CCSD) vibrational corrections to spin-spin coupling constants (SSCCs) computed at the level of vibrational second-order perturbation theory (VPT2) using the vibrational averaging driver of the CFOUR program. As CCSD calculations of vibrational corrections are very costly, cheaper electronic structure methods are explored via a newly developed Python vibrational averaging program within the Dalton Project. Namely, the second-order polarisation propagator approximation (SOPPA) and density functional theory (DFT) with the B3LYP and PBE0 exchange-correlation functionals are compared to the benchmark CCSD//CCSD(T) and experimental values. CCSD//CCSD(T) corrections are also combined with literature CC3 equilibrium values to form the highest-order vibrationally corrected values available i.e. CC3//CCSD(T) + CCSD//CCSD(T). CCSD//CCSD(T) statistics showed favourable statistics in comparison to experimental values, albeit at an unfavourably high computational cost. A cheaper CCSD//CCSD(T) + B3LYP method showed quite similar mean absolute deviation (MAD) values as CCSD//CCSD(T), concluding that CCSD//CCSD(T) + B3LYP is optimal in terms of cost and accuracy. With reference to experimental values, a vibrational correction was not worth the cost for all other methods tested. Finally, deviation statistics showed that CC3//CCSD(T) + CCSD//CCSD(T) vibrational corrected equilibrium values deteriorated in comparison to CCSD//CCSD(T) attributed to the use of a smaller basis and/or lack of solvation effects for the CC3 equilibrium calculations.
AB - Traditional nuclear magnetic resonance (NMR) calculations typically treat systems with a Born-Op penheimer-derived electronic wavefunction that is solved for a fixed nuclear geometry. One can numerically account for this neglected nuclear motion by averaging over property values for all nuclear geometries with a vibrational wavefunction and adding this expectation value as a correction to an equilibrium property value. Presented are benchmark coupled-cluster singles and doubles (CCSD) vibrational corrections to spin-spin coupling constants (SSCCs) computed at the level of vibrational second-order perturbation theory (VPT2) using the vibrational averaging driver of the CFOUR program. As CCSD calculations of vibrational corrections are very costly, cheaper electronic structure methods are explored via a newly developed Python vibrational averaging program within the Dalton Project. Namely, the second-order polarisation propagator approximation (SOPPA) and density functional theory (DFT) with the B3LYP and PBE0 exchange-correlation functionals are compared to the benchmark CCSD//CCSD(T) and experimental values. CCSD//CCSD(T) corrections are also combined with literature CC3 equilibrium values to form the highest-order vibrationally corrected values available i.e. CC3//CCSD(T) + CCSD//CCSD(T). CCSD//CCSD(T) statistics showed favourable statistics in comparison to experimental values, albeit at an unfavourably high computational cost. A cheaper CCSD//CCSD(T) + B3LYP method showed quite similar mean absolute deviation (MAD) values as CCSD//CCSD(T), concluding that CCSD//CCSD(T) + B3LYP is optimal in terms of cost and accuracy. With reference to experimental values, a vibrational correction was not worth the cost for all other methods tested. Finally, deviation statistics showed that CC3//CCSD(T) + CCSD//CCSD(T) vibrational corrected equilibrium values deteriorated in comparison to CCSD//CCSD(T) attributed to the use of a smaller basis and/or lack of solvation effects for the CC3 equilibrium calculations.
U2 - 10.26434/chemrxiv-2023-jj5jl
DO - 10.26434/chemrxiv-2023-jj5jl
M3 - Preprint
T3 - ChemRxiv
SP - 43
BT - Exploring Alternate Methods to High-Level Vibrational Correction Calculations of NMR Spin-Spin Coupling Constants
ER -
ID: 374348009