Non-empirical quantum-chemical calculations on ZSM-5 zeolites. I. Brønsted acid sites

1988 ◽  
Vol 417 (1852) ◽  
pp. 81-94 ◽  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Acid Sites ◽  
Basis Set ◽  
Hydroxyl Group ◽  
Oh Groups ◽  
Pc Cluster ◽  
Simulation Techniques ◽  
Proton Binding Energy ◽  
Standard Sets

This paper describes the study of the -OH group in ZSM-5 zeolite. The importance of zeolite ZSM-5 and the advantages in studying the OH groups by computer simulation techniques are highlighted. The methodology followed in the present study, which is a combination of classical and quantum-chemical calculations, is briefly described. The basis set SV3-21G has been chosen following trial calculations performed with different standard sets of basis functions. Results of geometrical optimizations carried out to determine the position of hydrogen in the ZSM-5 lattice are reported. The size of the point-charge (PC) cluster is varied and its effect on the calculated properties of the hydroxyl group is discussed. Calculations on a larger quantum-chemical (QC) cluster containing the hydroxyl group in both normalized and experimental structures reveal that geometry is an important factor for electronic properties. The procedure for generation of a suitable PC cluster to represent the rest of the lattice is described. Results of a calculation for a cluster model of 82 ions (PC cluster) in which a Si 2 O 7 (QC cluster) entity is explicitly treated by ab initio procedures, are discussed. The reported parameters include the O-H vibrational frequency, the proton binding energy and the aluminium substitution energy and we discuss their implications for the catalytic properties.

scholarly journals Geometric and energetic data from quantum chemical calculations of halobenzenes and xylenes

2020 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Software Package ◽  
Geometry Optimization ◽  
Theoretical Data ◽  
Basis Set ◽  
Chemical Calculation ◽  
Custom Made

<p>This article presents theoretical data on geometric and energetic features of halobenzenes and xylenes. Data were obtained from <i>ab initio</i> geometry optimization and frequency calculations at HF, B3LYP, MP2 and CCSD levels of theory on 6-311++G(d,p) basis set. In total, 1504 structures of halobenzenes, three structures of xylenes and one structure of benzene were generated and processed by custom-made codes in Mathematica. The quantum chemical calculation was completed in Q-Chem software package. Geometric and energetic data of the compounds are presented in this paper as supplementary tables. Raw output files as well as codes and scripts associated with production and extraction of data are also provided.</p>

scholarly journals Geometric and Energetic Data from Quantum Chemical Calculations of Halobenzenes and Xylenes

2020 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Software Package ◽  
Geometry Optimization ◽  
Theoretical Data ◽  
Basis Set ◽  
Chemical Calculation ◽  
Custom Made

<div>This article presents theoretical data on geometric and energetic features of halobenzenes and xylenes. Data were obtained from ab initio geometry optimization and frequency calculations at HF, B3LYP, MP2 and CCSD levels of theory on 6-311++G(d,p) basis set. In total, 1504 structures of halobenzenes, three structures of xylenes and one structure of benzene were generated and processed by custom-made codes in Mathematica. The quantum chemical calculation was completed in Q-Chem software package. Geometric and energetic data of the compounds are presented in this paper as supplementary tables. Raw output files as well as codes and scripts associated with production and extraction of data are also provided.</div>

scholarly journals GoodVibes: automated thermochemistry for heterogeneous computational chemistry data

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 291 ◽  
Author(s):  
Guilian Luchini ◽  
Juan V. Alegre-Requena ◽  
Ignacio Funes-Ardoiz ◽  
Robert S. Paton
Keyword(s):  
Harmonic Oscillator ◽  
Computational Chemistry ◽  
Open Source ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Basis Set ◽  
Partition Functions ◽  
Rigid Rotor ◽  
Computational Data ◽  
Publication Quality

GoodVibes is an open-source Python toolkit for processing the results of quantum chemical calculations. Thermochemical data are not simply parsed, but evaluated by evaluation of translational, rotational, vibrational and electronic partition functions. Changes in concentration, pressure, and temperature can be applied, and deficiencies in the rigid rotor harmonic oscillator treatment can be corrected. Vibrational scaling factors can also be applied by automatic detection of the level of theory and basis set. Absolute and relative thermochemical values are output to text and graphical plots in seconds. GoodVibes provides a transparent and reproducible way to process raw computational data into publication-quality tables and figures without the use of spreadsheets.

scholarly journals Geometric and energetic data from quantum chemical calculations of halobenzenes and xylenes

2020 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Software Package ◽  
Geometry Optimization ◽  
Theoretical Data ◽  
Basis Set ◽  
Chemical Calculation ◽  
Custom Made

<p>This article presents theoretical data on geometric and energetic features of halobenzenes and xylenes. Data were obtained from <i>ab initio</i> geometry optimization and frequency calculations at HF, B3LYP, MP2 and CCSD levels of theory on 6-311++G(d,p) basis set. In total, 1504 structures of halobenzenes, three structures of xylenes and one structure of benzene were generated and processed by custom-made codes in Mathematica. The quantum chemical calculation was completed in Q-Chem software package. Geometric and energetic data of the compounds are presented in this paper as supplementary tables. Raw output files as well as codes and scripts associated with production and extraction of data are also provided.</p>

DFT Studies and Quantum Chemical Calculations of Benzoyl Thiourea Derivatives Linked with Morpholine and Piperidine for the Evaluation of Antifungal Activity

2022 ◽  
Vol 12 ◽  
Author(s):  
Rameshwar K. Dongare ◽  
Shaukatali N. Inamdar ◽  
Radhakrishnan M. Tigote
Keyword(s):  
Antifungal Activity ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Basis Set ◽  
Functional Study ◽  
Chemical Parameters ◽  
Thiourea Derivatives ◽  
Quantum Chemical Parameters ◽  
B3lyp Method

Herein, we report the density functional study of benzoyl thiourea derivatives linked to morpholine and piperidine to evaluate their antifungal activity. Overall six compounds BTP 1-3 and BTM 4-6 were optimized with DFT using the B3LYP method with 6-31G(d,p) basis set. The molecular geometry, bond lengths, bond angles, atomic charges and HOMO-LUMO energy gap have been investigated. The structural parameters have been compared with the reported experimental results and structure- antifungal activity relationship is explored in details. The calculated results from DFT were discussed using all Quantum chemical parameters of the compounds. Introduction: Benzoyl thiourea derivatives linked with morpholine and piperidine were reported to have good antifungal activity. Objective: To find the correlations between the quantum chemical calculations and the antifungal activity for the benzoyl thiourea derivatives linked with morpholine and piperidine. Method: Optimization was carried out with DFT using B3LYP method utilizing 6-31G(d,p) basis set. Results: A good correlation between the quantum chemical calculations and the antifungal activity for the benzoyl thiourea derivatives linked with morpholine and piperidine was found. Conclusion: The DFT study of benzoyl thiourea derivatives linked to morpholine and piperidine was evaluated for their antifungal activity and it showed good correlations of activity with the quantum chemical parameters.

scholarly journals Americium(iii) and europium(iii) complex formation with lactate at elevated temperatures studied by spectroscopy and quantum chemical calculations

2014 ◽  
Vol 43 (29) ◽  
pp. 11221-11232 ◽  
Author(s):  
Astrid Barkleit ◽  
Jerome Kretzschmar ◽  
Satoru Tsushima ◽  
Margret Acker
Keyword(s):  
Complex Formation ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Elevated Temperatures ◽  
Hydroxyl Group ◽  
Spectroscopic Techniques ◽  
Ft Ir

Spectroscopic techniques (NMR and ATR FT-IR) in combination with calculations (DFT) show that the hydroxyl group of the lactate is deprotonated under complex formation with Eu(iii).

Molecular and Electronic Structure of 1-Naphtol : Ab Initio Molecular Orbital and Density Functional Study

2011 ◽  
Vol 110-116 ◽  
pp. 1862-1869
Author(s):  
G. Raja ◽  
K. Saravanan ◽  
S. Sivakumar
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Raman Spectra ◽  
Quantum Chemical ◽  
Density Functional ◽  
Computational Method ◽  
Basis Set ◽  
Mode Analysis ◽  
Functional Study ◽  
Infrared And Raman Spectra

The molecular vibrations of 1-Naphtol were investigated in polycrystalline sample, at room temperature, by FT- IR and FT-Raman spectroscopy. In parallel, ab initio and various density functional (DFT) methods were used to determine the geometrical, energetic and vibrational characteristics of 1-Naphtol . On the basis of B3LYP/6-31G* and B3LYP/6-311+G** methods and basis set combinations, a xnormal mode analysis was performed to assign the various fundamental frequencies according to the total energy distribution (TED). The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The Infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Simulation of Infrared and Raman spectra, utilizing the results of these calculations led to excellent overall agreement with observed spectral patterns. The investigation is performed using quantum chemical calculations conducted by means of the Gaussian 98W and Guassview set of programs. Further, density functional theory (DFT) combined with quantum chemical calculations to determine the first-order hyperpolarizability.

AN INFRARED STUDY OF THE ADSORPTION OF AMMONIA ON POROUS VYCOR GLASS

1964 ◽  
Vol 42 (4) ◽  
pp. 802-809 ◽  
Author(s):  
N. W. Cant ◽  
L. H. Little
Keyword(s):  
Hydrogen Exchange ◽  
Lone Pair ◽  
Acid Sites ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Infrared Study ◽  
Vycor Glass ◽  
Oh Groups ◽  
Surface Hydroxyl ◽  
Adsorption Sites

The infrared spectrum of ammonia adsorbed on porous glass at 20 °C and 150 °C has been studied in the region 1450–4000 cm−1. No absorption band due to the asymmetric bending mode of ammonia was observed but in the NH stretching region, bands occurred at 3280 cm−1, 3320 cm−1, 3365 cm−1, and 3400 cm−1. The bands at 3320 cm−1 and 3400 cm−1 were easily removed by evacuation and are due to ammonia molecules hydrogen bonded through the nitrogen atom to surface hydroxyl groups. The bands at 3280 cm−1 and 3365 cm−1 were not removed by evacuation even at 150 °C and are due to ammonia molecules held to surface Lewis acid sites by the nitrogen lone-pair electrons. The site for this adsorption is not a surface hydroxyl group. These results are further evidence for the existence of the two adsorption sites proposed by Folman and Yates. Deuteration of the surface OH groups was easily accomplished with D2O vapor at 300 °C and the rate of hydrogen exchange between adsorbed ammonia molecules and surface OD groups was found to be rapid.

Sign in / Sign up

Export Citation Format

Share Document