scholarly journals Potential Functions and Thermodynamic Properties of UC, UN, and UH

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Shuang-Ling Tang ◽  
Yu Wang ◽  
Qi-Ying Xia ◽  
Xue-Hai Ju
Keyword(s):  
Configuration Interaction ◽  
Density Functional ◽  
Least Square Method ◽  
Potential Functions ◽  
Least Square ◽  
Basis Set ◽  
Dissociation Energies ◽  
Anharmonicity Constant ◽  
Different Temperatures ◽  
Relationship Of

Potential energy surface scanning for UC, UN, and UH was performed by configuration interaction (CI), coupled cluster singles and doubles (CCSD) excitation, quadratic configuration interaction (QCISD (T)), and density functional theory PBE1 (DFT-PBE1) methods in coupling with the ECP80MWB_AVQZ + 2f basis set for uranium and 6 − 311 + G∗ for carbon, hydrogen, and nitrogen. The dissociation energies of UC, UN, and UH are 5.7960, 4.5077, and 2.6999 eV at the QCISD (T) levels, respectively. The calculated energy was fitted to the potential functions of Morse, Lennard-Jones, and Rydberg by using the least square method. The anharmonicity constant of UC is 0.0047160. The anharmonic frequency of UC is 780.27 cm−1 which was obtained based on the PBE1 results. For UN, the anharmonicity constant is 0.0049827. The anharmonic frequency is 812.65 cm−1 which was obtained through the PBE1 results. For UH, the anharmonicity constant is 0.017300. The anharmonic frequency obtained via the QCISD (T) results is 1449.8 cm−1. The heat capacity and entropy in different temperatures were calculated using anharmonic frequencies. These properties are in good accordance with the direct DFT-UPBE1 results (for UC and UN) and QCISD (T) results (for UH). The relationship of entropy with temperature was established.

Quantitative Structure-activity Relationship Analysis for Predicting Lipophilicity of Aniline Derivatives (Including some Pharmaceutical Compounds)

2019 ◽  
Vol 22 (5) ◽  
pp. 333-345
Author(s):  
Morteza Rezaei ◽  
Esmat Mohammadinasab ◽  
Tahere Momeni Esfahani
Keyword(s):  
Density Functional ◽  
Pharmaceutical Compounds ◽  
Partial Least Square ◽  
Least Square ◽  
Basis Set ◽  
Van Der Waals Volume ◽  
Relationship Analysis ◽  
Aniline Derivatives ◽  
Aqueous Solvent ◽  
Qsar Models

Background: In this study, we used a hierarchical approach to develop quantitative structureactivity relationship (QSAR) models for modeling lipophilicity of a set of 81 aniline derivatives containing some pharmaceutical compounds. Objective: The multiple linear regression (MLR), principal component regression (PCR) and partial least square regression (PLSR) methods were utilized to construct QSAR models. Materials & Methods: Quantum mechanical calculations at the density functional theory level and 6- 311++G** basis set were carried out to obtain the optimized geometry and then, the comprehensive set of molecular descriptors was computed by using the Dragon software. Genetic algorithm (GA) was applied to select suitable descriptors which have the most correlation with lipophilicity of the studied compounds. Results: It was identified that such descriptors as Barysz matrix (SEigZ), hydrophilicity factor (Hy), Moriguchi octanol-water partition coefficient (MLOGP), electrophilicity (ω/eV) van der Waals volume (vWV) and lethal concentration (LC50/molkg-1) are the best descriptors for QSAR modeling. The high correlation coefficients and the low prediction errors for MLR, PCR and PLSR methods confirmed good predictability of the three models. Conclusion: In present study, the high correlation between experimental and predicted logP values of aniline derivatives indicated the validation and the good quality of the resulting three regression methods, but MLR regression procedure was a little better than the PCR and PLSR methods. It was concluded that the studied aniline derivatives are not hydrophilic compounds and this means these compounds hardly dissolve in water or an aqueous solvent.

The Theory Investigation for the Antioxidant Activity of Phloretin: A Comparation with Naringenin

2014 ◽  
Vol 513-517 ◽  
pp. 359-362
Author(s):  
Ming Xun Yan ◽  
Jin Dong Gong ◽  
Ping Shen ◽  
Chang Ying Yang
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Density Functional ◽  
Radical Scavenging ◽  
Basis Set ◽  
Hydroxyl Groups ◽  
Bond Dissociation Energies ◽  
Functional Theory ◽  
Dissociation Energies ◽  
Radical Scavenging Properties

Density functional theory (DFT) calculations, based on B3LYP/6-311G (d, p) basis set, were performed to evaluate the OH bond dissociation energies (BDEs) for phloretin, compared with naringenin, in order to assess the contribution of hydroxyl groups at different position to the radical-scavenging properties. It is indicated clearly that A6 OH is determined as the weakest O-H bond, give rise to the smallest BDE, 73.98 kcal/mol. BDE of B4 OH decreases 2.5 kcal/mol in benzene, very close to that of A6OH, indicated that B4 OH group is also mainly contributed to the reaction with free radicals, especially in non-polar environments.

THEORETICAL STUDIES ON BOND DISSOCIATION ENERGIES FOR SOME THIOL COMPOUNDS BY DENSITRY FUNCTIONAL THEORY AND CBS-Q METHOD

2008 ◽  
Vol 07 (05) ◽  
pp. 943-951 ◽  
Author(s):  
XIAO-HONG LI ◽  
ZHENG-XIN TANG ◽  
ABRAHAM F. JALBOUT ◽  
XIAN-ZHOU ZHANG ◽  
XIN-LU CHENG
Keyword(s):  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Basis Sets ◽  
Q Method ◽  
Bond Dissociation Energies ◽  
Functional Theory ◽  
Thiol Compounds ◽  
Bond Dissociation ◽  
Dissociation Energies

Quantum chemical calculations are used to estimate the bond dissociation energies (BDEs) for 15 thiol compounds. These compounds are studied by employing the hybrid density functional theory (B3LYP, B3PW91, B3P86, PBE0) methods and the complete basis set (CBS-Q) method together with 6-311G** basis set. It is demonstrated that B3P86 and CBS-Q methods are accurate for computing the reliable BDEs for thiol compounds. In order to test whether the non-local BLYP method suggested by Fu et al.19 is general for our study and whether B3P86 method has a low basis set sensitivity, the BDEs for seven thiol compounds are also calculated using BLYP/6-31+G* and B3P86 method with 6-31+G*, 6-31+G**, and 6-311+G** basis sets for comparison. The obtained results are compared with the available experimental results. It is noted that B3P86 method is not sensitive to the basis set. Considering the inevitable computational cost of CBS-Q method and the reliability of the B3P86 calculations, B3P86 method with a moderate or a larger basis set may be more suitable to calculate the BDEs of the C–SH bond for thiol compounds.

scholarly journals An Accurate and Efficient Method to Predict Y-NO Bond Homolysis Bond Dissociation Energies

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Hong Zhi Li ◽  
Lin Li ◽  
Zi Yan Zhong ◽  
Yi Han ◽  
LiHong Hu ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Basis Set ◽  
Bond Dissociation Energies ◽  
Data Set ◽  
Test Set ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Bond Homolysis

The paper suggests a new method that combines the Kennard and Stone algorithm (Kenstone, KS), hierarchical clustering (HC), and ant colony optimization (ACO)-based extreme learning machine (ELM) (KS-HC/ACO-ELM) with the density functional theory (DFT) B3LYP/6-31G(d) method to improve the accuracy of DFT calculations for the Y-NO homolysis bond dissociation energies (BDE). In this method, Kenstone divides the whole data set into two parts, the training set and the test set; HC and ACO are used to perform the cluster analysis on molecular descriptors; correlation analysis is applied for selecting the most correlated molecular descriptors in the classes, and ELM is the nonlinear model for establishing the relationship between DFT calculations and homolysis BDE experimental values. The results show that the standard deviation of homolysis BDE in the molecular test set is reduced from 4.03 kcal mol−1calculated by the DFT B3LYP/6-31G(d) method to 0.30, 0.28, 0.29, and 0.32 kcal mol−1by the KS-ELM, KS-HC-ELM, and KS-ACO-ELM methods and the artificial neural network (ANN) combined with KS-HC, respectively. This method predicts accurate values with much higher efficiency when compared to the larger basis set DFT calculation and may also achieve similarly accurate calculation results for larger molecules.

scholarly journals Effect Of Sodium Dodecyl Sulfate On Viscometric Properties Of Methanol, Ethanol, n-Propanol And iso-Propanol At Different Temperatures

2013 ◽  
Vol 25 (2) ◽  
pp. 110-123 ◽  
Author(s):  
MA Motin ◽  
MA Hafiz Mia ◽  
AKM Nasimul Islam ◽  
KM Salim Reza ◽  
MA Yousuf
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Sodium Dodecyl ◽  
Least Square Method ◽  
Chemical Society ◽  
Alcohol Concentration ◽  
Least Square ◽  
Ternary Mixtures ◽  
Excess Viscosities ◽  
Dodecyl Sulfate ◽  
Different Temperatures

The critical micelle concentration (CMC) of Sodium Dodecyl Sulfate (SDS) in water was determined from the conductance and viscosity measurement. The estimated value of CMC was found to be 0.0085 mol.L-1 at 29°C. The concentration of SDS in pre-micellar and post-micellar region of 0.005M and 0.01M, respectively were used for the viscometric measurements of Methanol, Ethanol, n-Propanol, iso-Propanol at different temperatures. Viscosities of ternary mixtures of Methanol, Ethanol, n- Propanol and iso-Propanol in 0.005M and 0.01M aqueous SDS have been studied over the entire range of composition at 298.15- 323.15K with an interval of 5K except Methanol. Methanol system was studied at 298.15-308.15K owing to its low boiling point. Viscosities increase rapidly with alcohol concentration and show maxima in aqueous SDS rich region at 0.2 – 0.3 mole fraction of alcohols. The position of maxima virtually does not change remarkably with the variation of temperature. The excess viscosities, ?E values are found to be positive and large in magnitude, indicating that aqueous SDS solutions of alcohols are highly non ideal. The heights of the maxima are in the order:iso-Propanol + aqueous SDS > n-Propanol + aqueous SDS > Ethanol + aqueous SDS > Methanol + aqueous SDS.The excess viscosities, ?E data have been fitted by the least square method to the four parameter Redlich-Kister equation and the values of the parameter aj have been reported. Journal of Bangladesh Chemical Society, Vol. 25(2), 110-123, 2012 DOI: http://dx.doi.org/10.3329/jbcs.v25i2.15046

Application of Ab Initio Quantum Mechanical Calculations to Investigate Oxidation of C-7 and C-14 Methyl Esters: An Alternative Fuel

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
I. Shafagh ◽  
K. J. Hughes ◽  
M. Pourkashanian
Keyword(s):  
Density Functional ◽  
Methyl Esters ◽  
Carbon Number ◽  
Software Tool ◽  
State Theory ◽  
Basis Set ◽  
Bimolecular Reactions ◽  
Dissociation Energies ◽  
Complete Basis Set ◽  
The One

Using the GAUSSIAN 03 (Frisch et al., 2004, GAUSSIAN 03, Revision C.02, Gaussian, Inc., Wallingford, CT) program, the electronic structure of the C-14 and C-7 methyl esters, C14H28O2 (methyl tridecanoate) and C7H14O2 (methyl hexanoate), was estimated. For the electronic calculations, the density functional theory at the B3LYP/6-311G(d,p) level and the complete basis set (CBS-QB3) were applied. Bond dissociation energies for C-14 and C-7 esters were evaluated and compared with those of methyl butanoate, C5H10O2. Using the KHIMERA program (2007, KHIMERA04, Version 1.1, Motorola Inc; Novoselov et al., 2002, “CHIMERA: A Software Tool for Reaction Rate Calculations and Kinetics and Thermodynamics Analysis,” J. Comput. Chem., 23, pp. 1375–1389), contributions from energies, harmonic vibrational frequencies, and moments of inertia were utilized to construct modified Arrhenius rate expressions for bimolecular reactions. C7H14O2 was selected as a surrogate for the C14 fuel in order to study the bimolecular reactions with flame radicals. In the present work, reactions of carbon numbers 4 and 5 of C7H14O2, where carbon number 1 is the one single bonded to oxygen atom, with flame reactive radicals such as CH3, HO2, and H were studied where the rates for the reactions of other carbon sites can be obtained from studying methyl butanoate’s reactions. The rate expressions were estimated using transition state theory as implemented in KHIMERA over the temperature of 500–2000 K.

scholarly journals Electronic structure and dosage correlation of 1,4-benzodiazepines

2019 ◽  
Vol 10 (2) ◽  
pp. 108-112
Author(s):  
Raghdaa Adel Massoud ◽  
Mohamed Abdalla Makhyoun
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Atomic Charge ◽  
Least Square Method ◽  
Least Square ◽  
Molecular Volume ◽  
Homo And Lumo ◽  
Linear Least Square

Density functional theory was used to calculate the electronic structure of 20 selected 1,4-benzodiazepine derivatives. Certain parameters were extracted from the theoretical calculations, including the proton affinity of N1, the total energy, HOMO and LUMO energies, the total positive atomic charge, dipole moment and molecular volume. These parameters were used for the correlation with the minimum effective dose acting on human. The correlation was performed by applying linear least square method. Seven parameters were found to afford good fit. Clorazepate, one of the benzodiazepines, was studied extensively, it contains a carboxylate group, which can act as an ordinary molecule or zwitterions, where the ionisable proton migrates to N1. The energy gap between the two forms was found to be strongly dependent on the solvent dielectric constant.

scholarly journals Dampak E-Servive Quality Terhadap E-Satisfaction Serta Implikasinya Pada Online Repurchase B2C Shopee.com

2020 ◽  
Vol 10 (1) ◽  
pp. 109-118
Author(s):  
Raras Ivastya ◽  
Zaenal Fanani
Keyword(s):  
Service Quality ◽  
Least Square Method ◽  
Partial Least Square ◽  
Least Square ◽  
Online Questionnaire ◽  
Online Data ◽  
Partial Least Square Method ◽  
Relationship Of ◽  
The Relationship ◽  
Positive Effect

Internet services that were introduced in 1993 have an impact on behavior change and the ways of consumer decisions making. On the other hand, the emergence of various developments in information technology, connectivity and smartphones are also slowly able to change the way of consumers for meet the needs of a product or service. This research was conducted for intention to examine the effect of e-service quality on e-satisfaction and implications on B2C consumer repurchase online. Data was taken using an online questionnaire and distributed to B2C consumers with the last amount of data collected as many as 312 questionnaires and then be analyzed using the partial least square method. The results of the analysis show that e-service quality provides a significant positive effect on e-satisfaction and online repurchase for B2C consumers. In other results show e-satisfaction has a significant effect on online repurchase and is able to be a partial mediator of the relationship of e-service quality with online repurchase of B2C consumers.

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