Study on structures and electronic properties of neutral and anionic TiSin(0,-1)(n = 1–8) clusters using G4 theory

2014 ◽  
Vol 13 (05) ◽  
pp. 1450038 ◽  
Author(s):  
Jun Lu ◽  
Jucai Yang ◽  
Zhifei Xing ◽  
Hongmei Ning
Keyword(s):  
Experimental Data ◽  
Ground State ◽  
Electronic Structures ◽  
Electron Affinities ◽  
Average Absolute Deviation ◽  
Absolute Deviation ◽  
Relative Stabilities ◽  
Dissociation Energies ◽  
Ground State Structures ◽  
Experimental Values

The geometries, electronic structures and energies of small TiSi n species (n = 1–8) and their anions were systematically investigated by G4 theory. The ground-state structures of these clusters are presented herein. For neutral TiSi n (n = 1–8), the spin multiplicities of the ground-state structures are singlet, with the exception of n = 2, which exists in a triplet state. For anionic TiSi n-, the spin multiplicities of the ground-state structures are doublet, with the exception of n = 2, which is quartet. The adiabatic electron affinities for TiSi n are estimated to be 1.31 eV ( TiSi ), 1.46 eV ( TiSi 2), 1.53 eV ( TiSi 3), 1.71 eV ( TiSi 4), 2.06 eV ( TiSi 5), 2.16 eV ( TiSi 6), 2.20 eV ( TiSi 7) and 2.39 eV ( TiSi 8). In comparison with the available experimental data, the calculated adiabatic electron affinities differ from experimental values by an average absolute deviation of only 0.03 eV. Additionally, the dissociation energies of Ti atoms from TiSi n, and Si atoms from TiSi n and Si n clusters are estimated to examine relative stabilities.

scholarly journals A Thermochemical Computational Study on Hydroxyquinolines and their Azulene Analogues

2018 ◽  
Author(s):  
Moyassar Meshhal ◽  
Safinaz El-Demerdash ◽  
Ahmed El-Nahas
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Enthalpies Of Formation ◽  
Mean Absolute Deviation ◽  
Electron Affinities ◽  
Absolute Deviation ◽  
The Mean ◽  
Experimental Values ◽  
Theory And Experiment ◽  
Good Agreement

Ab initio CBS-QB3 method has been used to determine gas-phase enthalpies of formation for 34 compounds including a number of hydroxyquinoline isomers, the corresponding azulene analogues and their parent systems. The mean absolute deviation of 4.43 kJ/mol reveals good agreement between our results and the available experimental data. Relative thermodynamic stabilities of hydroxyquinoline isomers and related analogues were discussed and several isomerization reactions enthalpies were derived. The same level of theory has also been utilized to calculate adiabatic ionization energies and electron affinities for the molecules with known experimental values and the agreement between theory and experiment was found to be within 8 kJ/mol.

scholarly journals Density, Enthalpy of Vaporization and Local Structure of Neat N-Alkane Liquids

Liquids ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 47-59
Author(s):  
Gerrick E. Lindberg ◽  
Joseph L. Baker ◽  
Jennifer Hanley ◽  
William M. Grundy ◽  
Caitlin King
Keyword(s):  
Chemical Processes ◽  
Distribution Functions ◽  
Average Absolute Deviation ◽  
Average Deviation ◽  
Absolute Deviation ◽  
Amber Force Field ◽  
Local Structures ◽  
Ideal Solution Behavior ◽  
Experimental Values ◽  
Dynamics Simulations

The properties of alkanes are consequential for understanding many chemical processes in nature and industry. We use molecular dynamics simulations with the Amber force field GAFF2 to examine the structure of pure liquids at each respective normal boiling point, spanning the 15 n-alkanes from methane to pentadecane. The densities predicted from the simulations are found to agree well with reported experimental values, with an average deviation of 1.9%. The enthalpies of vaporization have an average absolute deviation from experiment of 10.4%. Radial distribution functions show that short alkanes have distinct local structures that are found to converge with each other with increasing chain length. This provides a unique perspective on trends in the n-alkane series and will be useful for interpreting similarities and differences in the n-alkane series as well as the breakdown of ideal solution behavior in mixtures of these molecules.

A Thermochemical Computational Study on Hydroxyquinolines and their Azulene Analogues

2018 ◽  
Author(s):  
Moyassar Meshhal ◽  
Safinaz El-Demerdash ◽  
Ahmed El-Nahas
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Enthalpies Of Formation ◽  
Mean Absolute Deviation ◽  
Electron Affinities ◽  
Absolute Deviation ◽  
The Mean ◽  
Experimental Values ◽  
Theory And Experiment ◽  
Good Agreement

Ab initio CBS-QB3 method has been used to determine gas-phase enthalpies of formation for 34 compounds including a number of hydroxyquinoline isomers, the corresponding azulene analogues and their parent systems. The mean absolute deviation of 4.43 kJ/mol reveals good agreement between our results and the available experimental data. Relative thermodynamic stabilities of hydroxyquinoline isomers and related analogues were discussed and several isomerization reactions enthalpies were derived. The same level of theory has also been utilized to calculate adiabatic ionization energies and electron affinities for the molecules with known experimental values and the agreement between theory and experiment was found to be within 8 kJ/mol.

Electronic structures and second hyperpolarizabilities of alkaline earth metal complexes end-capped with NA2 (A = H, Li, Na)

2016 ◽  
Vol 18 (18) ◽  
pp. 12505-12520 ◽  
Author(s):  
Paramita Banerjee ◽  
Prasanta K. Nandi
Keyword(s):  
Metal Complexes ◽  
Ground State ◽  
Electronic Structures ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Basis Sets ◽  
Alkaline Earth Metal ◽  
Nlo Properties ◽  
Ground State Structures

The ground state structures and NLO properties of a number of alkaline earth metal complexes end-capped with NA2 groups (A = H, Li, Na) are calculated by employing the CAM-B3LYP, wB97XD and B2PLYP functionals along with MP2 and CCSD(T) for 6-311++G(d,p), 6-311++G(3df,3pd), aug-cc-pVTZ, aug-pc-2 and Hypol basis sets.

Applicability of Emulsion Viscosity Models to Crude Oil Emulsion

2012 ◽  
Vol 581-582 ◽  
pp. 50-53 ◽  
Author(s):  
Li Ping Guo ◽  
Lei Wang ◽  
Yi Min Zhang
Keyword(s):  
Experimental Data ◽  
Crude Oil ◽  
Apparent Viscosity ◽  
Least Square ◽  
Model Parameters ◽  
Average Absolute Deviation ◽  
Absolute Deviation ◽  
Oil Emulsion ◽  
Waxy Crude ◽  
Water Cut

The rheology behavior of waxy crude emulsion is an important basic information on safeguard research of crude oil-water flow. The non-newtonian characteristics of apparent viscosity of three kinds of waxy crude emulsions were studied experimentally around condensation point; three apparent viscosity forecasting models were evaluated by least-square regressions based on experimental data of shear balance and the average absolute deviation was taken as the measurement of fitness of a model to experimental data. It is concluded that the Pal-Rhodes model, whose relative deviation can be as high as 80%, is the worst forecasting model, but it need the least experiment data to obtain model parameters, only water cut was needed. Elgibaly model has the best forecasting results, the average absolute deviation of forecasting results of three waxy crude emulsions under the condition of different temperature, water cut and shear rate were all less than 15%, but compared with the other two models, Elgibaly model needs the most parameters.

scholarly journals Theoretical Study for Potential Energy Curves, Dissociation Energy and Molecular Properties for (LiH, H2, HF) Molecules

2015 ◽  
Vol 59 ◽  
pp. 137-146
Author(s):  
Adil Nameh Ayaash
Keyword(s):  
Binding Energy ◽  
Potential Energy ◽  
Electronic Properties ◽  
Ground State ◽  
Theoretical Study ◽  
Potential Energy Curves ◽  
Spectroscopic Constants ◽  
Electron Affinities ◽  
Dissociation Energies ◽  
Gaussian Program

A theoretical study has been carried out of calculating dissociation energies and potential energy curves (Deng-Fan potential and Varshni potential) and molecular parameters of of ground state of diatomic molecules (LiH, H2, HF). Dissociation energies and potential energy curves depended on spectroscopic constants (ωe, ωexe, re, α, μ, β ,) and our results has been compared with experimental results. Molecular and electronic properties as εHOMO, εLUMO, ionization potentials (IP), electron affinities (EA) and binding energy was performed by using B3P86/6-311++g** method and Gaussian program 03, the results is well in a agreement with that of other researchers.

Structures and electronic properties of WmMon (m + n ≤ 7) clusters

2018 ◽  
Vol 32 (04) ◽  
pp. 1850041
Author(s):  
Zhicheng Yu ◽  
Xiurong Zhang ◽  
Peiying Huo ◽  
Kun Gao
Keyword(s):  
Ground State ◽  
Electronic Structures ◽  
Density Functional ◽  
Geometry Optimization ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Ground State Structures ◽  
The Stability ◽  
D Orbitals

Geometric and electronic structures of W[Formula: see text]Mo[Formula: see text] (m + n [Formula: see text] 7) clusters have been systematically calculated by density functional theory (DFT) at the generalized gradient approximation (GGA) level for ground-state structures. Geometry optimization shows that clusters are almost bipyramid structures with m + n [Formula: see text] 4. E[Formula: see text] of clusters is mainly dominated by W atoms. And the substitution of atoms between W and Mo in Mo[Formula: see text] or W[Formula: see text] (n [Formula: see text] 7) clusters enhances the stability of the original clusters. The calculated IE shows that W[Formula: see text]Mo, W[Formula: see text]Mo2, W[Formula: see text]Mo3 and WMo[Formula: see text] are relatively more stable in the chemical reaction. In addition, the magnetism of clusters mainly comes from valance d orbitals.

Density functional theory for N–NO2 bond dissociation energies of N-nitroacylamide compounds in acetonitrile — Theoretical method assessment and prediction

2012 ◽  
Vol 90 (6) ◽  
pp. 526-533
Author(s):  
Xiaohong Li ◽  
Huixian Wang ◽  
Zhumu Fu ◽  
Xianzhou Zhang
Keyword(s):  
Density Functional ◽  
Substituent Effects ◽  
Theoretical Method ◽  
Bond Dissociation Energies ◽  
Absolute Deviation ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Maximum Absolute Deviation ◽  
Electron Withdrawing Group ◽  
Experimental Values

The performance of various density functional theories (B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, and MPWB95) was examined for calculating N–NO2 bond dissociation energies (BDEs) of 10 N-nitroacylamide compounds. The CBS-4M method was also used. By comparing the calculated results with the experimental values, it was observed that B1LYP/6–31G** and B3LYP/6–31+G** provided accurate BDEs. Especially, B3LYP/6–31+G** was recommended because of its smaller maximum absolute deviation. Further, substituent effects based on the B3LYP/6–31+G** method were analyzed. The result shows that an electron-donating group increases the BDE of the parent C6H5–CON(CH3)NO2, while an electron-withdrawing group decreases the BDE of the parent C6H5–CON(CH3)NO2. Subsequently, the BDEs of the other N-nitroacylamindes were estimated.

scholarly journals Rotational Ground-State Bands of ¹⁶⁸Hf Nucleus

2021 ◽  
Vol 3 (5) ◽  
pp. 34-36
Author(s):  
I. Hossain ◽  
Hewa Y. Abdullah ◽  
M. A. Saeed ◽  
M. O. Alzanbaqi ◽  
Fadhil I. Sharrad
Keyword(s):  
Experimental Data ◽  
Ground State ◽  
Empirical Formula ◽  
Remarkable Degree ◽  
Experimental Values ◽  
Semi Empirical

This paper has been explained to study the rotational arrangement of even-even 168Hf isotope using the phenomenological fitting, Sood’s semi-empirical formula. The rotational energies from the calculated values were compared to the experimental data. The result shows that in 168Hf, calculated energies fit the experimental values to a remarkable degree of accuracy.

A Model for Extending the Heptanes plus Fraction for Trinidad Gas Condensates

2014 ◽  
Author(s):  
R.. Mayrhoo ◽  
R.. Hosein
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Compositional Data ◽  
Distribution Functions ◽  
Gas Condensate ◽  
Accurate Description ◽  
Average Absolute Deviation ◽  
Absolute Deviation ◽  
Mole Percent ◽  
Gas Condensates

Abstract An accurate description of pseudo-component compositions is required for Equation of State predictions for gas condensate systems. Very often these extended experimental data are unavailable and must be generated using mathematical models, of which the exponential and the three-parameter gamma distribution functions are the two most widely used. The development of these two techniques was based on the assumption of a continuous molar relationship for pseudo-components. However, experimental compositional data for gas condensate systems show discontinuities in this relationship at SCN8 and SCN13. The above models when applied to extend the C7+ fraction for Trinidad gas condensates, under predict the SCN8 mole percent and over predict the SCN12 mole percent due to the aforementioned discontinuities. The Average Absolute Deviation between the predicted and experimental SCN8 and SCN12 data were both greater than 25 percent. The two coefficient method described by Ahmed et al., when applied to extend the C7+ fraction, reduced the discontinuity at SCN8 to less than 12 percent. However the SCN12 group still had a deviation greater than 18 percent. These results show that existing models were not designed to take care of these discontinuities and should be used with caution when extending experimental data beyond SCN7. The Model described in this study resolves these discontinuities in the molar relationships at both SCN8 and SCN12 with an Average Absolute Deviation between the predicted and experimental compositions of less than 10 percent. This model can quite easily be included in Equation of State packages for a more accurate description of compositions for Trinidad gas condensates for performing compositional simulation studies. A partial analysis beyond the C7+ fraction is not required with this new model.

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