Basis set dependence of SO stretching frequencies and its consequences for IR and VCD spectra predictions

2020 ◽  
Vol 22 (48) ◽  
pp. 27979-27986
Author(s):  
Kevin Scholten ◽  
Elric Engelage ◽  
Christian Merten
Keyword(s):  
Ir Spectra ◽  
Model Systems ◽  
Basis Set ◽  
Polarization Functions

Using chiral tosylates as model systems we evaluate the effect of diffuse and polarization functions on the quality of predicted VCD and IR spectra. Polarization functions on sulfur are shown to be important to reliable determine ACs using VCD.

A Comprehensive Computational Study on OCH+-Rg (Rg = He, Ne, Ar, Kr, Xe) Complexes

2003 ◽  
Vol 68 (3) ◽  
pp. 489-508 ◽  
Author(s):  
Yinghong Sheng ◽  
Jerzy Leszczynski
Keyword(s):  
Computational Study ◽  
Relativistic Effects ◽  
Dft Method ◽  
Basis Set ◽  
Rare Gas ◽  
Geometrical Parameters ◽  
Minor Effect ◽  
Dissociation Energies ◽  
Equilibrium Geometries

The equilibrium geometries, harmonic vibrational frenquencies, and the dissociation energies of the OCH+-Rg (Rg = He, Ne, Ar, Kr, and Xe) complexes were calculated at the DFT, MP2, MP4, CCSD, and CCSD(T) levels of theory. In the lighter OCH+-Rg (Rg = He, Ne, Ar) rare gas complexes, the DFT and MP4 methods tend to produce longer Rg-H+ distance than the CCSD(T) level value, and the CCSD-calculated Rg-H+ bond lengths are slightly shorter. DFT method is not reliable to study weak interaction in the OCH+-He and OCH+-Ne complexes. A qualitative result can be obtained for OCH+-Ar complex by using the DFT method; however, a higher-level method using a larger basis set is required for the quantitative predictions. For heavier atom (Kr, Xe)-containing complexes, only the CCSD method predicted longer Rg-H+ distance than that obtained at the CCSD(T) level. The DFT method can be applied to obtain the semiquantitative results. The relativistic effects are expected to have minor effect on the geometrical parameters, the H+-C stretching mode, and the dissociation energy. However, the dissociation energies are sensitive to the quality of the basis set. The nature of interaction between the OCH+ ion and Rg atoms was also analyzed in terms of the interaction energy components.

Net charges and valence AO's in the methylamines; the hydrogen basis set and the properties of nitrogen

1985 ◽  
Vol 63 (7) ◽  
pp. 1487-1491 ◽  
Author(s):  
Giuseppe Del Re ◽  
Sándor Fliszár ◽  
Michel Comeau ◽  
Claude Mijoule
Keyword(s):  
Basis Set ◽  
Basis Sets ◽  
Methyl Groups ◽  
Extended Form ◽  
Amine Nitrogen ◽  
Methyl Group ◽  
Net Charges ◽  
Extended Basis

Net charges and valence AO's for ammonia, methylamine, dimethylamine, and trimethylamine were calculated using extended basis sets. Superposition effects, evaluated by replacing Pople's standard 6-31G* basis by an extended form in which the basis of the ammonia H atoms and of the methyl groups of trimethylamine are retained in the treatment of each molecule, indicate that the quality of the treatment of amine nitrogen atoms is strongly dependent on the number of methyl groups. A new, augmented basis is proposed for the hydrogens, which appears to be reasonably well balanced: comparison with familiar (e.g., 6-31G*) calculations illustrates in what manner the treatment of nitrogen is worsened when even just one methyl group is replaced by hydrogen unless the impoverishment of the basis is suitably taken care of.

Comparison of the Conformational Stability for Several Vinylhalomethanes and Silanes with Experiment Using MP2 Perturbation Theory and DFT

2007 ◽  
Vol 72 (1) ◽  
pp. 15-50 ◽  
Author(s):  
Wolfgang Förner ◽  
Hassan M. Badawi
Keyword(s):  
Experimental Data ◽  
Vibrational Spectra ◽  
Recent Literature ◽  
Conformational Stability ◽  
Basis Set ◽  
Major Conclusion ◽  
Stable Conformer ◽  
Polarization Functions ◽  
Complete Series ◽  
Triple Zeta

In recent literature it was reported that the valence triple zeta basis set augmented by polarization functions is not too reliable for vinyl monohalo- and dihalomethanes and -silanes, the halogen being fluorine and chlorine. The major conclusion was that a valence triple zeta basis is too small to be augmented by polarization functions in a balanced way, at least on vinylmonofluoromethane. Thus we decided to apply the 6-311++G** basis set to the complete series of methanes, silanes and germanes (the latter ones are just added for completeness because no experimental data are available for them and, moreover, we published them already previously) and to compare the results to experimental data available in the literature to see whether the failures of this basis set show up in the complete series of molecules. In the literature we found five such molecules and the information which of the conformers is the most stable. Indeed we found that predictions on the relative stability of conformers in those systems with this basis set and MP2 as well as DFT are with a 60:40 chance, three being correct predictions and two being incorrect ones out of the five. However, since the energy differences are rather small in these systems and due to the fact that - as a consequence of twofold degeneracy of the gauche conformer on the potential curve of the torsional vibration - the abundances of the conformers in equilibrium do not change too much, we decided to calculate also vibrational spectra for three examples and to compare them also to experiment. It is reported that besides the failures in total energy (we have chosen two examples where predictions of the nature of the stable conformer are correct, and one where it is not), the vibrational spectra are rather well reproduced, especially when experimental energies are used to calculate abundances in equilibrium in the case where the prediction of the stable conformer failed.

86 Impact of Community-Level Socioeconomic Disparities on Quality of Life After Burn Injury: A Burn Model Systems Database Study

2021 ◽  
Vol 42 (Supplement_1) ◽  
pp. S59-S60
Author(s):  
Stephanie A Mason ◽  
Emma L Gause ◽  
Helena Archer ◽  
Stephen H Sibbett ◽  
Radha K Holavanahalli ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Burn Injury ◽  
Well Being ◽  
Community Level ◽  
Model Systems ◽  
Socioeconomic Disparities ◽  
Injury Incidence ◽  
The Impact ◽  
Zip Code

Abstract Introduction Individual- and community-level socioeconomic disparities impact overall health and injury incidence, severity, and outcomes. However, the impact of community-level socioeconomic disparities on recovery after burn injury is unknown. We aimed to characterize the association between community-level socioeconomic disparities and health-related quality of life (HRQL) after burn injury. These findings might inform rehabilitation service delivery and policy making at administrative levels. Methods Participants with the NIDILRR Burn Model System who were ≥14 years with a zip code were included. Sociodemographic and injury characteristics and 12-item Short Form Health Survey (SF-12) and Veterans RAND (VR-12) physical (PCS) and mental (MCS) component summary scores 6 months after injury were extracted. Data were deterministically linked by zip code to the Distressed Communities Index (DCI), which combines seven census-derived metrics into a single indicator of economic well-being that ranges from 0 (lowest distress) to 100 (highest distress). Multilevel linear regression models estimated the association between DCI and HRQL. Results The 342 participants were mostly male (239, 69%) had a median age of 48 years (IQR 33–57) and sustained a median burn size of 10% TBSA (IQR 3–28%). More than one-third of participants (117, 34%) lived in a neighborhood within the two most distressed quintiles. After adjusting for age, race/ethnicity, and pre-injury HRQL, increasing neighborhood distress was negatively associated with PCS (ß-0.05, SE 0.02, p=0.01). Age and pre-injury PCS were also significantly associated with 6-month PCS. There was no association between neighborhood distress and 6-month MCS. However, pre-injury MCS was significantly associated with 6-month MCS (0.56, SE 0.07, p< 0.001). Conclusions Neighborhood distress is associated with lower PCS after burn injury but is not associated with MCS. Regardless of neighborhood distress, pre-injury HRQL is significantly associated with both PCS and MCS during recovery.

Ab initio predictions of the zero field splittings and the singlet–triplet transition strengths for the n → π* transition of selenoformaldehyde

1993 ◽  
Vol 71 (10) ◽  
pp. 1706-1712 ◽  
Author(s):  
D.C. Moule ◽  
L. Chantranupong ◽  
R.H. Judge ◽  
D.J. Clouthier
Keyword(s):  
Energy Levels ◽  
Random Phase ◽  
Open Shell ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Hartree Fock ◽  
Lower Valence ◽  
Polarization Functions

The energy levels of the lower valence and Rydberg states of selenoformaldehyde, CH2Se, have been calculated by the SCF/CI method. Wavefunctions for the ROHF (restricted open shell Hartree–Fock) states were obtained with the Binnings–Curtis double-ζ basis set, augmented with Rydberg and polarization functions. Configuration interaction was applied to the parent configurations, PCMO (parent configuration molecular orbital). Oscillator strengths were evaluated for the allowed electric dipole transitions by the RPA (random phase approximation), and SOPPA (second-order polarization propagator approximation) methods. The spin-orbit contribution to the zero field splitting of the first triplet state, 3A2(n,π*) as well as the oscillator strengths to the three spin components were calculated by perturbation theory. These calculations predict that the Sx, Sy, and Sz components are shifted by −96.091,−96.707, and + 29.167 cm−1, respectively, from their unperturbed position. The oscillator strengths for the three components fx, fy, and fz of the 3A2(n,π*) ← 1A1(g.s.) transition were calculated to be 3.45 × 10−7, 1.15 × 10−7, and 173.0 × 10−7.

A Systematic abinitio LCAO–MO–SCF Study of the Ionization Potentials, Electron, Proton, Hydrogen, and Hydride Affinities of SHn Molecules and Ions

1975 ◽  
Vol 53 (24) ◽  
pp. 3747-3756 ◽  
Author(s):  
Roy E. Kari ◽  
Imre G.A Csizmadia
Keyword(s):  
Ionization Potentials ◽  
Basis Set ◽  
Charged Species ◽  
Polarization Functions ◽  
Gaussian Basis Set ◽  
Equilibrium Geometries ◽  
Lcao Mo

Equilibrium geometries and energies are obtained for SHn (n = 0, 1, 2, 3) neutral and charged species by the Roothaan LCAO–MO–SCF method. A large gaussian basis set including d and p polarization functions was employed. The calculated ionization potentials, electron, proton, hydrogen, and hydride affinities are discussed as well as compared with similar previously calculated properties for OHn (n = 0, 1, 2, 3) species.

scholarly journals Acoustic Pattern Recognition and Courtship Songs: Insights from Insects

2019 ◽  
Vol 42 (1) ◽  
pp. 129-147 ◽  
Author(s):  
Christa A. Baker ◽  
Jan Clemens ◽  
Mala Murthy
Keyword(s):  
Pattern Recognition ◽  
Sound Production ◽  
Relevant Information ◽  
Model Systems ◽  
Bird Songs ◽  
Neural Recordings ◽  
Behavioral Studies ◽  
Courtship Songs ◽  
Acoustic Pattern

Across the animal kingdom, social interactions rely on sound production and perception. From simple cricket chirps to more elaborate bird songs, animals go to great lengths to communicate information critical for reproduction and survival via acoustic signals. Insects produce a wide array of songs to attract a mate, and the intended receivers must differentiate these calls from competing sounds, analyze the quality of the sender from spectrotemporal signal properties, and then determine how to react. Insects use numerically simple nervous systems to analyze and respond to courtship songs, making them ideal model systems for uncovering the neural mechanisms underlying acoustic pattern recognition. We highlight here how the combination of behavioral studies and neural recordings in three groups of insects—crickets, grasshoppers, and fruit flies—reveals common strategies for extracting ethologically relevant information from acoustic patterns and how these findings might translate to other systems.

Basis set effects on the calculated bonding energies of neutral benzene dimers: importance of diffuse polarization functions

1996 ◽  
Vol 252 (3-4) ◽  
pp. 206-210 ◽  
Author(s):  
Seiji Tsuzuki ◽  
Tadafumi Uchimaru ◽  
Masuhiro Mikami ◽  
Kazutoshi Tanabe
Keyword(s):  
Basis Set ◽  
Polarization Functions

Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals

1998 ◽  
Vol 63 (9) ◽  
pp. 1409-1430 ◽  
Author(s):  
Miroslav Urban ◽  
Pavel Neogrády ◽  
Juraj Raab ◽  
Geerd H. F. Diercksen
Keyword(s):  
Large Deviation ◽  
Theoretical Calculations ◽  
Dipole Moments ◽  
Accuracy Assessment ◽  
Open Shell ◽  
Basis Set ◽  
Coupled Cluster ◽  
Hartree Fock ◽  
Experimental Values

Dipole moments of a series of radicals, OH, NO, NS, SF, SO, PO, ClO, CN, LiO, NO2, and ClO2 were calculated by the Coupled Cluster CCSD(T) method with the single determinant restricted open shell Hartree-Fock (ROHF) reference. For all molecules theoretical dipole moments were carefully compared to experimental values. The size and the quality of the basis set were systematically improved. Spin adaptation in the ROHF-CCSD(T) method, largest single and double excitation amplitudes and the T1 diagnostics were considered as indicators in the quality assessment of calculated dipole moments. For most molecules the accuracy within 0.01-0.03 D was readily obtained. For ClO and CN the spin adaptation was necessary - its contribution was as large as 0.03-0.045 D. Large deviation from experiment is observed for OH in its A2Σ+ excited state (0.135 D) and especially for LiO in its 2Π ground state (0.22 D). No indication of the failure of theoretical calculations was found which leads to the conclusion that, even if there is still a space for the improvement of theoretical calculations, experimental values should be reconsidered.

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