Papers by Stephan P. A. Sauer
Lytic polysaccharide monooxygenases (LPMOs) are enzymes that binds polysaccharides followed by an... more Lytic polysaccharide monooxygenases (LPMOs) are enzymes that binds polysaccharides followed by an (oxidative) disruption of the polysaccharide surface, thereby boosting depolymerization. The binding process between LPMO and polysaccharide is key to the mechanism and recent investigations have established structure-function relationships for this binding, employing hyperfine coupling constants (HFCs) from EPR spectroscopy. Unfortunately, EPR does not provide direct structural data and therefore the experimental EPR parameters have been supported with parameters calculated with density functional theory. Yet, calculated HFCs are extremely sensitive to the employed computational setup. Using the LPMO Ls(AA9)A, we here quantify the importance of several choices in the computational setup, ranging from the use of specialized basis, the underlying structures, and the employed exchange-correlation functional. We compare our results to both X-ray structures and experiment (EPR Model 1 Opt. without substrate Model 2 Model 3 H 2 O Cell (C 6 O 6 H 12 ) O Ax.
Calculation of the Indirect Spin-spin Coupling Constant Using Locally Dense Basis Sets
unne.edu.ar
Page 1. Calculation of the Indirect Spin-spin Coupling Constant Using Locally Dense Basis Sets Sa... more Page 1. Calculation of the Indirect Spin-spin Coupling Constant Using Locally Dense Basis Sets Sauer, Stephan PA1 - Provasi, Patricio F.2 - Aucar, Gustavo A.2 1.Chemistry Laboratory IV - Department of Chemistry - University of Copenhagen. ...
Molecular Physics, Feb 10, 2010
Vertical electronic excitation energies and one-electron properties of 28 medium-size molecules f... more Vertical electronic excitation energies and one-electron properties of 28 medium-size molecules from a previously proposed benchmark set are revisited using the augmented correlationconsistent triple-zeta aug-cc-pVTZ basis set in CC2, CCSDR(3), and CC3 calculations. The results are compared to those obtained previously with the smaller TZVP basis set. For each of the three coupled cluster methods, a correlation coefficient greater than 0.994 is found between the vertical excitation energies computed with the two basis sets. The deviations of the CC2 and CCSDR(3) results from the CC3 reference values are very similar for both basis sets, thus confirming previous conclusions on the intrinsic accuracy of CC2 and CCSDR(3). This similarity justifies the use of CC2-or CCSDR(3)-based corrections to account for basis set incompleteness in CC3 studies of vertical excitation energies. For oscillator strengths and excited-state dipole moments, CC2 calculations with the aug-cc-pVTZ and TZVP basis sets give correlation coefficients of 0.966 and 0.833, respectively, implying that basis set convergence is slower for these one-electron properties.
Physical Chemistry Chemical Physics, 2020
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Theoretical Chemistry Accounts, Feb 23, 2018
The basis set convergence of nuclear spin-spin coupling constants (SSCC) calculated at the couple... more The basis set convergence of nuclear spin-spin coupling constants (SSCC) calculated at the coupled cluster singles and doubles (CCSD) level has been investigated for ten difficult molecules. Eight of the molecules contain fluorine atoms and nine contain double or triple bonds. Results obtained using the ccJ-pVXZ, X=D,T,Q,5, hierarchy of basis sets of Benedikt et al. [J. Chem. Phys. 129, 064111 (2008)], converge rather slowly towards the basis set limit, but fast convergence can be obtained by adding diffuse functions, in particular for couplings across several bonds. The pcJ-n basis sets of Jensen [J. Chem. Theory Comput. 2, 1360 (2006)] exhibit large contraction errors for one-bond couplings, but in their uncontracted form they perform better than the ccJ-pVXZ basis sets. For multi-bond couplings, however, diffuse functions should be used, and when including these the two hierarchies show similar performance. The ccJ-pVXZ basis sets with diffuse functions included (aug-ccJ-pVXZ) show consistent performance across all types of SSCCs, with the triple zeta (X=T) basis set yielding sufficiently good results for most purposes.
Molecular Physics, May 19, 2020
Journal of Chemical Physics, Jun 21, 2020
The performance of different polarization propagator methods, RPA, RPA(D), HRPA, HRPA(D) and SOPP... more The performance of different polarization propagator methods, RPA, RPA(D), HRPA, HRPA(D) and SOPPA have been tested against CC3 values for both static and dynamic polarizabilities. The test set consists of 14 (hetero-)aromatic medium size organic molecules, mostly with a high degree of symmetry. The benchmark of the methods remarkably reveals that RPA and HRPA(D) yield results comparable with the CC3 values and that they outperform SOPPA for these molecules. For a subset of the molecules a comparison could be made to experimental values. The comparison for static polarizabilities proves that RPA and HRPA(D) as well as RPA(D) reproduce experimental values to a satisfying precision, whereas the SOPPA method compared to these two methods appears to perform only adequately. An investigation of the performance of Sadlej's polarized triple zeta basis set against Dunning's augcc-pVTZ basis set was also carried out. It is found, that in contrast to other methods, Sadlej's basis set did not perform sufficiently compared to the larger aug-cc-pVTZ basis set for the RPA based methods.
Molecular Physics, Jan 3, 2019
Journal of Chemical Physics, Jul 27, 2018
The pcJ-n basis set, optimized for spin-spin coupling constant calculations using density functio... more The pcJ-n basis set, optimized for spin-spin coupling constant calculations using density functional theory methods, are expanded to also include the s-block elements Li, Be, Na, and Mg, by studying several small molecules containing these elements. This is done by decontracting the underlying pc-n basis sets, followed by augmentation with additional tight functions. As was the case for the p-block elements, the convergence of the results can be significantly improved by augmentation with tight s-functions. For the p-block elements additional tight functions of higher angular momentum were also needed, but this is not the case for the s-block elements. A search for the optimum contraction scheme is carried out using the criterion that the contraction error should be lower than the inherent error of the uncontracted pcJ-n relative to the uncontracted pcJ-4 basis set. A large search over possible contraction schemes is done for the Li 2 and Na 2 molecules, and based on this search contracted pcJ-n basis sets for the four atoms are recommended. This work shows that it is more difficult to contract the pcJ-n basis sets, than the underlying pc-n basis sets. However, it also shows that the pcJ-n basis sets for Li and Be can be more strongly contracted than the pcJ-n basis sets for the p-block elements. For Na and Mg, the contractions are to the same degree as for the p-block elements.
Magnetic Resonance in Chemistry, May 16, 2021
The aug-cc-pVTZ-J basis set family is extended to include the fourth row p-block elements Ga, Ge,... more The aug-cc-pVTZ-J basis set family is extended to include the fourth row p-block elements Ga, Ge, As, Se and Br. We use the established approach outlined by Sauer and co-workers [
Electric Properties
Oxford University Press eBooks, Aug 25, 2011
Lytic polysaccharide monooxygenases (LPMOs) are enzymes that binds polysaccharides followed by an... more Lytic polysaccharide monooxygenases (LPMOs) are enzymes that binds polysaccharides followed by an (oxidative) disruption of the polysaccharide surface, thereby boosting depolymerization. The binding process between LPMO and polysaccharide is key to the mechanism and recent investigations have established structure-function relationships for this binding, employing hyperfine coupling constants (HFCs) from EPR spectroscopy. Unfortunately, EPR does not provide direct structural data and therefore the experimental EPR parameters have been supported with parameters calculated with density functional theory. Yet, calculated HFCs are extremely sensitive to the employed computational setup. Using the LPMO Ls(AA9)A, we here quantify the importance of several choices in the computational setup, ranging from the use of specialized basis, the underlying structures, and the employed exchange-correlation functional. We compare our results to both X-ray structures and experiment (EPR Model 1 Opt. without substrate Model 2 Model 3 H 2 O Cell (C 6 O 6 H 12 ) O Ax.
Implicit and explicit solvent models have opposite effects on radiation damage rate constant for thymine
Advances in Quantum Chemistry
Author response for "Azo‐hydrazone molecular switches: Synthesis and NMR conformational investigation
Prediction of the standard potentials for one-electron oxidation ofN,N,N′,N′ tetrasubstitutedp-phenylenediamines by calculation
Physical Chemistry Chemical Physics, 2021
It is important to investigate the effect of the basis set size and the treatment of electron cor... more It is important to investigate the effect of the basis set size and the treatment of electron correlation when calculating the one-electron oxidation potentials forN,N,N′,N′ tetrasubstitutedp-phenylenediamines.
Magnetic Properties
Molecular Electromagnetism, 2011
Perturbation Theory
Molecular Electromagnetism, 2011
Traditional nuclear magnetic resonance (NMR) calculations typically treat systems with a Born-Opp... more Traditional nuclear magnetic resonance (NMR) calculations typically treat systems with a Born-Oppenheimer-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
Response theory in the multipole reaction field model for equilibrium and nonequilibrium solvation: Exact theory and the second order polarization propagator approximation
Journal of Chemical Physics, Jul 30, 2003
Exact response functions are derived for a multipole solvent reaction field model of equilibrium ... more Exact response functions are derived for a multipole solvent reaction field model of equilibrium and nonequilibrium solvation using the generalized Ehrenfest theorem and assuming a spherical cavity surrounding the solute. The starting point is the Schrödinger equation and we shortly review how the reaction field is introduced into the Schrödinger equation in order to clearly identify the limitations of describing solute–solvent interactions with a reaction field model. The solvent is described as an isotropic homogeneous linear dielectric medium characterized by a static and an optical dielectric constant. From the exact response functions we derive linear response functions within the higher random phase and the second order polarization propagator approximation. Excitation energies, oscillator strengths, and polarizabilities are then calculated for solvated H2S and furan using the augmented correlation consistent triple-ζ (aug-cc-pVTZ) and double-ζ (aug-cc-pVDZ) basis sets for H2S and furan, respectively. We have also calculated excitation energies and oscillator strengths for H2S with standard (vacuum) ab initio methods using a variety of basis set, as there has been no previously reported values of these quantities calculated with the second order polarization propagator approximation. The second order polarization propagator approximation gives excitation energies and oscillator strengths close to values obtained by coupled cluster methods for a solvated H2S molecule, whereas the higher random phase approximation tends to overestimate the value of these quantities. The solvent effect of the excitation energies follow the same trends for all of the reaction field ab initio methods used in the present study, but some oscillator strengths show different solvent effects whether they are calculated with correlated or with noncorrelated ab initio methods. The calculated polarizabilities show the same solvent effect independent of any inclusion of dynamical electron correlation. It is also shown that the equilibrium solvation model is not appropriate for high-frequency perturbations.
Molecular Physics, Jun 16, 2020
The interfacial tension of systems containing water, n-decane, and model naphthenic acids were in... more The interfacial tension of systems containing water, n-decane, and model naphthenic acids were investigated using a predictive model based on COSMO-RS theory and experimental pendant drop measurements. Five naphthenic acid homologues that are considered to be representative of surfactants inherent to crude oil were dissolved in n-decane at equal concentrations. The interfacial tensions of the five systems at an acid concentration of 1.66 mol% relative to ndecane were experimentally determined to be 27-30 mN/m. The interfacial tensions of the five different acid-decane phases against water were also predicted using density functional theory (DFT) calculations and COSMO-RS theory. The accuracy of the predictions was very good as confirmed through pendant drop measurements of the interfacial tension. The mean-absolute-deviation between experimental and predicted values was 2.6 mN/m thus demonstrating the high predictive power of COSMO-RS theory for calculating the interfacial tension at oil-water interfaces in the presence of surface-activecompounds.
Uploads
Papers by Stephan P. A. Sauer