Sadlej Basis Sets Research Articles

Polarizability of Pyruvate Anion in Small Water Clusters

Pyruvate anion is important in a broad array of physicochemical processes ranging from glucose homeostasis to atmospheric reactions. However, the electronic polarizability of the moiety has not been investigated extensively. We present theoretical results from electronic structure calculations on the static and dynamic polarizability of microhydrated pyruvate anions. These investigations were carried out with the CH3COCOO[Formula: see text]n H2O clusters ([Formula: see text]–9) to mimic microhydration conditions. These density functional theory calculations were carried out at the B3LYP/aug-cc-PVTZ level to uncover the optimal geometry of the anion water cluster. Sadlej basis set functions with the B3LYP functional were used to calculate the static and dynamic polarizabilities. Multiple simulated annealing simulations were carried out to discover additional low-lying minima. It is observed that the electronic polarizability varies linearly with the size of the hydrated cluster. Expressions that describe the relationship between the dynamic polarizability and the field frequency are provided for each cluster.

Structural, energetic and response electric properties of cyclic selenium clusters: an ab initio and density functional theory study

The geometries, relative stabilities, binding energies, second-order difference of total energy (Δ2E), vertical ionization energies (VIEs), vertical electron affinities (VEAs) and dipole polarizabilities of neutral Se2 and cyclic Sen (n = 3–12) clusters have been systematically investigated using conventional ab initio [HF, MP2, MP3, MP4, CCSD, CCSD(T)] and density functional theory (B3LYP, CAM-B3LYP) levels with the Dunning’s correlation-consistent (cc-pVDZ, aug-cc-pVDZ, d-aug-cc-pVDZ and aug-cc-pVTZ) and Sadlej (POL and POL-DK) basis sets. For each cluster size, various structural isomers have been considered and optimized to search for the lowest-energy structure. The effects of the geometry, basis set and theoretical level on the calculated properties have been discussed. The relative stability of the clusters has been analyzed using binding energy per atom, Δ2E and VIE–VEA gap. The computed binding energies and VIEs have been compared with the available observed data. The calculated properties show a strong dependence upon the size and geometry of the cluster. The even-numbered Sen with n = 6 and 8 are predicted to be relatively stable clusters. The physico-chemical properties of selenium clusters have been compared to those of the sulphur homologues. On passing from sulphur to selenium clusters the binding energy per atom decreases, whereas the mean dipole polarizability per atom increases.

Comparative study of CCSD(T) and DFT methods: Electronic (hyper)polarizabilities of glycine

Static electronic (hyper)polarizabilities of the two lowest-energy conformations of glycine have been computed in the gas phase by using high-level ab initio and DFT methods with the POL, LPOLX-ds and LPOLX-fl Sadlej basis sets. Response electric properties from Hartree–Fock, Møller–Plesset and DFT computations have been compared to those calculated with Coupled-Cluster levels. Long-range corrected CAM-B3LYP and ωB97X-D functionals are superior to B3LYP, B3PW91 and mPW1PW91 especially to predict first- and second-order hyperpolarizabilities. The results obtained with the POL, LPOLX-ds and LPOLX-fl basis sets have minor differences. The effects of the different conformation on the response electric properties have been illustrated.

Ab initio and DFT study of the static dipole (hyper)polarizabilities of benzaldehyde and thio-benzaldehyde molecules in gas phase

The results of ab initio and density functional theory DFT calculations of dipole moments and electronic contributions to static dipole (hyper)polarizabilities of benzaldehyde and thiobenzaldehyde molecules in gas phase are presented. These properties were evaluated at the SCF, MP2, MP4 and DFT (B3LYP) levels of theory with a selection of basis sets that include polarization and diffuse functions on the C, O, S and H atoms: 6-31+G(d,p) (A), 6-311++G(3d,3p) (B), 6-31+G(d*,p) (C) and the Sadlej (D) basis sets, using HF/A, MP2/A and B3LYP/A optimized geometries under the Cs symmetry restriction. The C basis set has been optimized in terms of the maxima second hyperpolarizability at HF level. Both MP2 and MP4 methods, performed at full electron configuration, have shown to perform well in the calculation of such properties. Considering the basis sets effects, the impact of the electron correlation in the (hyper)polarizabilities of these molecules is analyzed systematically in terms of the differences between MP2 and MP4 perturbation theory and those from DFT(B3LYP) methods. The effects of substitution of the C=S fragment by the C=O group in the benzaldehyde molecule, giving the formation of thiobenzaldehyde, lead to enhanced results of nonlinear optical properties in terms of their first (β) and second hyperpolarizability (γ), that shown to be higher than those for para-Nitroaniline molecules. In fact, thiobenzaldehyde exhibit significant values of nonlinear optical properties which make this chromophore a prospective building block for nonlinear optical materials.

Excited state polarizabilities of methanol clusters

An ab initio investigation of the polarizabilities of the first two excited states of methanol clusters [(CH(3)OH)(n), n = 1-12] has been carried out employing time dependent density functional theory with B3LYP exchange correlation functional using 6-311++G(d,p) and Sadlej basis sets. Good linear correlations have been demonstrated for the first and second excited state polarizabilities as a function of the aggregation number (n) of the methanol clusters. On the contrary, for water clusters the variations of excited state polarizabilities with cluster size are found to be non-monotonic. The variations of the excitation energies and oscillator strengths with n for the first three excited states of methanol clusters and water clusters are also reported.

Induction effects in metal cation–benzene complexes

The role of polarization in the stabilization of a series of biologically relevant alkali and alkaline-earth metal cations (Li(+), Na(+), K(+), Mg(2+) and Ca(2+)) with the pi-electron distribution of benzene is examined by means of MP2 computations using Sadlej's basis set. In all cases a full description of the energy profile for the approach of the metal cation along the axis normal to the molecular plane of benzene has been performed. Analysis of the different contributions to the interaction energy, performed within the framework of the symmetry-adapted perturbation theory (SAPT), illustrates the important role of the induction component in the definition of the geometrical and energetic properties of the pathway leading to the formation of cation-pi complex. Finally, the ability of classical polarization models based on models of implicitly and explicitly interacting distributed isotropic polarizabilities to describe the induction term has been examined and discussed in the context of the generation of new polarizable force fields.

Density Functional Static Dipole Polarizability and First-Hyperpolarizability Calculations of Nan (n = 2, 4, 6, 8) Clusters Using an Approximate CPKS Method and its Comparison with MP2 Calculations.

We report the static dipole polarizability and first-hyperpolarizability of the sodium atom clusters, Nan, n = 2, 4, 6 and 8, using our recent implementation of a numerical-analytical approach to the coupled-perturbed Kohn-Sham (CPKS) equations in deMon2k. The calculations are reported for VWN and BP86 exchange-correlation functionals using Sadlej and TZVP-FIP1 basis sets which have been previously optimized for polarizability calculations. All-electron calculations were performed for the optimizations at the VWN/DZVP/A2 and PW86/DZVP/A2 levels. Comparisons are made with Hartree-Fock (HF) and MP2 benchmark calculations.

B3LYP study of the dipole moment and the static dipole (hyper)polarizabilities of para‐nitroaniline in gas phase

AbstractThe dipole moment μ and the electronic (hyper)polarizabilities α, β, and γ tensors of paranitroaniline (PNA) has been calculated in the static regime with the B3LYP hybrid approach of the density functional theory (DFT) formalism and by using the numerical triple finite field method of Kamada et al. The calculations were performed with planar C2v optimized geometry and the standard 6‐31+G(d,p), d optimized 6‐31+G(d*,p) and the specialized Sadlej basis sets. The B3LYP/6‐31+G(d*,p) results of μ, α, β, and γ are comparable to those of the literature. In particular, the static average γ of PNA is comparable to MP2 calculations and is able to reproduce 54% of the experimental static value from Z‐scan experiments recently reported. The origin of the differences between the experimental and theoretical values is discussed. The findings emphasize the use of the DFT methodology in conjunction with optimized basis sets for a reasonable estimated of the electron correlation in static second hyperpolarizability calculations of push–pull conjugated molecules. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006

An augmented effective core potential basis set for the calculation of molecular polarizabilities

Calculations of molecular polarizabilities require basis sets capable of accurately describing the responses of the electrons to an external perturbation. Unfortunately, basis sets that yield suitable quantitative results have traditionally been all-electron sets with large numbers of primitives, making their use computationally intractable even for moderately sized systems. We present a systematic augmentation of the effective core potential basis set of Stevens et al. [J Chem Phys 81, 12 (1984), Can J Chem 70, 612 (1992)] for 39 main group elements based on the procedure used to construct diffuse and polarization functions in the well-known Sadlej basis sets [Collec Czech Chem Comm 53, 1995 (1988)]. Representative calculations have been performed and we have shown that results to within 1% of all-electron calculations using the Sadlej basis set can be obtained for <1-35% of the computational cost using this new basis set.

Electronic dipole polarizability and hyperpolarizability of formic acid

The electric dipole polarizability and hyperpolarizability of the cis and trans form of formic acid have been calculated at CCSD(T) and DFT levels of theory using Dunning and Sadlej basis sets. The frequency-dependent (hyper)polarizabilities have been obtained for different non-linear optical processes. Dispersion corrections are found to be very modest for 〈 α〉(− ω; ω) but sizeable for β v(− ω σ ; ω 1, ω 2) and 〈 γ〉(− ω σ ; ω 1, ω 2, ω 3). DFT, within the B3LYP and PBE1PBE approximations, gives accurate values of dipole moment and dipole polarizability, but seriously overestimates first and second hyperpolarizabilities. It has been found that cis and trans conformations of formic acid could be easily distinguished on the basis of their first hyperpolarizability and depolarization ratio values.

Determination of ab initio absolute Raman excitation profiles using linear response theory

AbstractA study of the computational requirements for the calculation of Raman‐related properties is presented, and the importance of the inclusion of electronic correlation and basis sets on the convergence of absolute Raman intensities and depolarization ratios for a set of small polyatomic systems (H2O, NH3, CH4, and C2H2) is discussed. These properties are derived from the geometric gradients of the dynamic polarizabilities evaluated with linear response equations. The Complete Active Space Self‐Consistent Field (CASSCF) static correlation effects as well as the effects of dynamic electronic correlation at the Møller‐Plesset Second‐Order Perturbation Theory (MP2), approximate Coupled Cluster Singles and Doubles (CC2), and Coupled Cluster Singles and Doubles (CCSD) levels on these properties were investigated and are presented. Basis set convergence for the series aug‐cc‐pV(D,T,Q)Z were analyzed. The results obtained using Sadlej's polarizability basis set are also presented. While the MP2 level produces good relative Raman intensities, it is shown that accurate absolute intensities require high‐level correlated wave functions (CCSD). The importance of static correlation effects for the Raman intensities is assessed. Large basis sets are required to predict Raman intensities accurately (aug‐cc‐pVTZ), but Sadlej's basis set is shown to be the best choice to compute these properties for large molecules. Depolarization ratios showed little dependency on the basis set and the theoretical level. It was determined that the correlation effects on geometric gradients of polarizabilities are associated mainly with molecular polarizabilities, and not with normal coordinates. The optimal size of the atomic displacements used to compute numerical derivatives of polarizabilities without influencing the Raman properties derived from them was ascertained. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Static Dipole Polarizability of o-, m- and p-Benzyne isomers: Ab initio, DFT and CCSD calculations

We report a study of the static dipole polarizability (α) of the o-, m- and p-benzyne isomers in their singlet ground state. Due to the biradical character of benzynes, calculations were performed at ab initio unrestricted Hartree-Fock (UHF) level of theory. The correlation effects were accounted for with second order Moller Plesset (MP2) method, Density Functional Theory (DFT) with the BLYP and B3LYP hybrid approaches and the coupled cluster CCSD method with 6-31$+$G(d,p) standard basis set with optimized geometries. C$_2$v symmetry restriction was employed for the geometry of o- and m-benzynes (closed and open conformation) and D$_2$h for p-benzynes (open and closed conformation). Because the high quality of the basis set is a requirement for accurate α determination, MP2 and DFT calculations were performed with the 6-31+G(d,p), the extended 6-311++G(3d,3p) and the specialized Sadlej basis sets. The CCSD calculations were only carried out with the 6-31+G(d,p) and the Sadlej basis sets. The results indicate that the average α polarizability values for o- and m-benzynes are lower than the corresponding to the experimental value of benzene, while this property for p-benzyne is slightly higher than the benzene one. The anisotropy Δα values of benzyne isomers are always higher than the anisotropy of benzene molecule. Finally, was found that the conformations of p-C$_6$H$_4$are the less stable isomers, and are the most polarizables and anisotropic compounds from the benzyne series.

Assignment of Vibrational Spectra of 1,10-Phenanthroline by Comparison with Frequencies and Raman Intensities from Density Functional Calculations

NIR−FT-Raman spectra of 1,10-phenanthroline were recorded of crystalline material and three different solutions (CD3OD, CHCl3, and CS2) in the wavenumber range 100−1800 cm-1. FT-IR spectra of the solid material were obtained for the range 400−1800 cm-1. A complete assignment of the experimental vibrational spectra (IR and Raman) of 1,10-phenanthroline is given on the basis of calculated frequencies and Raman intensities obtained from the DFT(BP86) harmonic force field. A satisfactory agreement of the harmonic BP86 wavenumbers with the fundamental experimental ones is found. This good agreement is due to a systematic error compensation for BP86 harmonic force fields. Raman intensities were calculated within the double harmonic approximation with different basis sets in order to investigate whether moderately sized triple-ζ basis sets with comparatively few polarization functions can properly describe nonresonant Raman scattering. A satisfactory agreement with experimental data for all in-plane vibrations is already obtained with a standard valence triple-ζ basis plus polarization functions. However, for out-of-plane modes, we found a pronounced dependence of frequencies and intensities on the basis set size, which can be well understood by comparison with the results obtained with a larger basis set. The Sadlej basis set, which is recommended for the calculation of electrical properties, leads to deviations of up to 90 cm-1 for out-of-plane vibrations. Since 1,10-phenanthroline is hygroscopic and can hardly be obtained in water-free form, particular attention is paid to the influence of bound solvent molecules, like water and methanol, on the vibrational spectrum. Model systems with single solvent molecules attached to the isolated phenanthroline molecule were studied. It was found that the wavenumber shifts induced are generally small.

Segment polarizabilities for microelectrostatic calculations in poly(ethylene oxide)

Static polarizabilities of linear ether molecules are calculated using the DFT/B3LYP functional and the Sadlej basis set. A set of segment polarizabilities reproducing the total molecular polarizability is derived. Additivity and transferability of the obtained parameterization is tested on molecules in different conformations and on cyclic ethers. Relation of the calculated values to the static electric susceptibility of polyethylene and poly(ethylene oxide) is discussed.

Calculation of the gas phase specific rotation of ( S)-propylene oxide at 355 nm

The experimental gas phase specific rotation of ( S)-propylene oxide at 355 nm is correctly predicted at the DFT/B3LYP level of theory only adopting fairly large basis sets, such as aug-cc-pVTZ and aug-cc-pVQZ, or, alternatively, the much smaller polarizability-consistent Sadlej basis set. Therefore, considering also the sensitivity to solvent effects, this small and rigid molecule, which has been considered an ideal test case for theoretical investigations, is, on the contrary, one of the most difficult cases to be treated.

A way to compare experimental and SCRF electronic static dipole polarizability of pure liquids

When the polarizability tensor is computed through Self-Consistent Reaction Field Models (the interactions between solute and solvent are incorporated into calculation), there still exists a need to take into account the modifications of the applied macroscopic fields at the local site of the solvated molecule (the phenomenon historically indicated as ‘local field effects’). Another way is to remove local field factors from experimental mean polarizability ( α ̄ ) and polarizability anisotropy (Δ α) values. The present paper focuses on this way. Seven liquids (CS 2, C 6H 6, (CH 3) 2CO, CHCl 3, CH 2Cl 2, CH 3CN, CCl 4) have been studied. In a first step, the α tensor components have been computed at the B3LYP and HF levels with Sadlej basis set using a finite field procedure. The solvent effect is introduced into the calculation through the Self-Consistent Isodensity Polarizable Continuum Model (SCIPCM). In a second step, experimental literature values of refractive index, density, isothermal compressibility coefficient and depolarization ratio have been carefully chosen and introduced in modified experimental equations (where local field factors have been removed) to determine α ̄ and Δ α. Concerning α ̄ , there is a good agreement between experimental and B3LYP values for dipolar molecules. In the case of non-dipolar molecules calculated values are always lower than experimental ones. Such a behaviour had not been observed in a previous study concerning molecules in the gas state, therefore it seems that the SCIPCM induces a deficiency over calculated α ̄ (0) in the case of non-dipolar molecules.

Characterization of Metal Centers in Bioinorganic Complexes Using Ab Initio Calculations of113Cd Chemical Shifts

Determination of (113)Cd chemical shift is of significant interest in NMR characterization of metal porphyrins, metal-histidine interactions, and other metal-ligand interactions in many bioinorganic complexes and metalloproteins. In this study, we present a detailed account of a number of quantum chemical investigations aimed at relating isotropic and anisotropic (113)Cd chemical shifts to the structure of several biologically relevant complexes with discrete and polymeric structures. Calculated and experimentally determined chemical shift values are compared to correlate the variation of the chemical shift values with the structural changes around the metal center. Our results infer that the density functional theory using the Sadlej basis set on the cadmium atom is a suitable method for estimating cadmium shielding values to a reasonable accuracy.

Coupled-cluster Raman intensities: Assessment and comparison with multiconfiguration and density functional methods

An extensive study of static and dynamic Raman intensities is presented for normal vibrations of small molecules obtained with different correlated quantum chemical methods: namely, coupled-cluster, multiconfiguration self-consistent-field, and density functional theories. While this is the first systematic study of coupled-cluster (CC) Raman intensities considering also the dispersion effect for molecules with more than two atoms, another purpose of this study is the analysis of the accuracy of density functional Raman activities with respect to those from highly correlated ab initio methods in order to evaluate the validity of density functional theory for the calculation of Raman spectra for large molecules. The density functional intensities compare sufficiently well with those from ab initio methods. While the dynamic multiconfigurational intensities always compare well with the experimental values, they are usually smaller than those from density functional and coupled-cluster theories. The Raman intensities obtained from static coupled-cluster calculations are in better agreement with experiment than those from dynamic calculations, which should yield improved results as the dispersion effect is taken into account. Furthermore, Raman intensities obtained from the CC2 model are compared to those from CCSD calculations. It is found that the CC2 Raman activities deviate from the CCSD reference data. Particularly for the coupled-cluster Raman intensities the widely used Sadlej basis set leads to results which can be significantly improved on by using larger basis sets.

Linear and nonlinear optical properties of pyridine N-oxide molecule

This paper presents an investigation of the structure, dipole moment, dipole polarizability, first hyperpolarizability and second hyperpolarizability properties of pyridine N-oxide molecule. These properties were calculated at the static regime with fully C 2 v optimized geometries by using Hartree–Fock theory, second order perturbation Møller–Plesset MP2 methods, BLYP and B3LYP hybrid approaches within the density functional theory (DFT) framework, and CCSD methods, with the 6-31+G(d,p), 6-311++G(3d,3p) and Sadlej basis sets, and the gaussian 98 suite of programs. Similar calculations were also performed for pyridine molecule, and comparison between their properties was made.

Static and dynamic dipole polarizabilities of 2‐ and 3‐methylthiophenes in solution: experimental and theoretical determination

AbstractThe dynamic and static dipole polarizabilities of 2‐methythiophene (2MT) and 3‐methylthiophene (3MT) molecules were investigated using refractometric and theoretical calculations. The experimental properties were studied within the Garito and Singer approach for dilute CCl4 and CH3CN solutions. The local field effects were tested with the Onsager and Lorentz local fields. The static dipole polarizabilities of 2MT and 3MT were obtained from extrapolation to zero frequency of the corresponding dispersion Cauchy‐type curves, which gave a monotonic increase as a function of the squared frequency. The differences between these curves were analyzed as a function of the solvent effects and the local fields. The theoretical static properties were evaluated by using ab initio (Hartree–Fock) and density functional theory (DFT) (BLYP and B3LYP) methods with the 6–31 + G(d,p), 6–311 ++ G(3d,3p) and Sadlej basis sets. The dynamic polarizabilities were calculated with the time‐dependent Hartree–Fock (TDHF) approach and the 6–31 + G(d,p) and Sadlej basis sets. In order to make a comparison with the experimental results, the solvent effects were studied at the TDHF level in both CCl4 and CH3CN solvents and the Onsager model. The calculations were performed with fully optimized geometries. The experimental values of the static dipole polarizabilities of the 2MT and 3MT were determined as 1.129 × 10−21 and 1.140 × 10−21 esu, respectively, whereas the corresponding B3LYP/6–311 ++ G(3d,3p) values were 1.151 × 10−21 and 1.139 × 10−21 esu, respectively. Additionally, for the B3LYP/Sadlej method the corresponding values were 1.176 × 10−21 and 1.174 × 10−21 esu, respectively. In general, there was good agreement between the experimental and the DFT theoretical results. Copyright © 2002 John Wiley &amp; Sons, Ltd.