Study of potential curves by UHF type methods. Inversion and dissociation of NH3 molecule

1984 ◽  
Vol 49 (8) ◽  
pp. 1731-1735 ◽  
Author(s):  
Viliam Klimo ◽  
Jozef Tiňo
Keyword(s):  
Experimental Data ◽  
Saddle Point ◽  
Basis Set ◽  
Inversion Barrier ◽  
Exact Methods ◽  
Energy Parameters ◽  
Dissociation Energies ◽  
Bond Functions ◽  
Potential Curves ◽  
Good Agreement

Geometry and energy parameters of individual dissociation intermediate steps of the NH3 molecule, geometry of the saddle point, and the inversion barrier of NH3 have been calculated by the UMP2 method in the minimum basis set augmented with the bond functions. A good agreement has been reached with experimental data and with results of more exact methods except for the dissociation energies of the NH3 and NH2 molecules. New values of heats of formation are suggested on the basis of these results: ΔHfo0 = 197 and 362 kJ/mol for the NH2 and NH molecules, respectively.

Study of potential curves by UHF type methods. CH4 molecule and its dissociation products

1986 ◽  
Vol 51 (4) ◽  
pp. 731-737
Author(s):  
Viliam Klimo ◽  
Jozef Tiňo
Keyword(s):  
Experimental Data ◽  
Quantum Chemistry ◽  
High Energy ◽  
Basis Set ◽  
Electronic Correlation ◽  
Exact Methods ◽  
Energy Parameters ◽  
Bond Functions ◽  
The Individual ◽  
Potential Curves

Geometry and energy parameters of the individual dissociation intermediate steps of CH4 molecule, parameters of the barrier to linearity and singlet-triplet separation of the CH2 molecule have been calculated by means of the UMP method in the minimum basis set augmented with the bond functions. The results agree well with experimental data except for the geometry of CH2(1A1) and relatively high energy values of CH(2II) and CH2(1A1) where the existence of two UHF solutions indicates a necessity of description of the electronic correlation by more exact methods of quantum chemistry.

Conformational Structure of Chloromethyldichlorophosphines

2002 ◽  
Vol 57 (6-7) ◽  
pp. 333-336
Author(s):  
Evgenii A. Romanenko ◽  
Alexander M. Nesterenko
Keyword(s):  
Experimental Data ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Basis Set ◽  
Conformational Structure ◽  
Gauche Conformation ◽  
Nuclear Quadrupole ◽  
Set Up ◽  
Good Agreement

IThe 35Cl nuclear quadrupole resonances (77 K) and ab initio calculations of trichloromethyldichlorophosphine () show that it exists in the chess conformation form. The barrier to internal rotation about the P-C bond in I at the RHF/6-31++ G(d,p) level equals to 38.1 kJ mol-1. In chloromethyldichlorophosphine (II) the extension of the basis set up to the RHF/6-311++G(df, pd) level does not improve the description of the most preferable gauche-conformation; only if electron correlation (at the MP2 level) is taken into account the results are in a good agreement with experimental data.

scholarly journals GEOMETRICAL AND ELECTRONIC STRUCTURE OF PROPYL-, TETRAMETHYL-, DIMETHYLETHYL- AND BUTYLADAMANTANES AND THEIR THERMODYNAMIC CHARACTERISTIC ACCORDING TO DFT

2018 ◽  
Vol 61 (12) ◽  
pp. 108-114
Author(s):  
Amanzhan T. Saginayev ◽  
Evgenii I. Bagrii
Keyword(s):  
Experimental Data ◽  
Qualitative Agreement ◽  
Isopropyl Alcohol ◽  
Analytical Calculation ◽  
Dft Method ◽  
Energy Functional ◽  
Basis Set ◽  
Stationary Points ◽  
Important Conclusion ◽  
Good Agreement

Propyladamantanes were synthesized by alkylation of adamantane with isopropyl alcohol in the temperature range from 5 to 40 °C in the presence of 96% sulfuric acid. Tetramethyl- and dimethylethyladamantanes were synthesized by isomerization of perhydroanthracene in the presence of aluminium oxide catalyst on the setup of the flow type. Isomers of butyladamantanes were obtained by the reaction of alkylation of the adamantane with isooctane. For each molecule, the optimization of the geometric parameters of atoms was carried out using analytical calculation methods. By calculating the frequencies of normal vibrations using the second derivatives, it was confirmed that the stationary points determined by optimizing the geometry correspond to the minima of the potential energy surface. The structure of 1-n-propyladamantane (I), 1-isopropyl-adamantane (II), 2-n-propyladamantane (III), 1,2-di-n-propyladamantane (IV), 1,3-dimethyl-5-ethyladamantane (V), 1,3,5,6-tetramethyladamantane (VI), 1,3,5,7-tetramethyladamantane (VII), perhydroanthracene (VIII), 1-n-butyladamantane (IX), 1-isobutyladamantane (X), 1-sec-butyladamantane (XI) has been studied using the DFT method with the Becke–Lee–Yang–Parr hybrid energy functional of electron density with the 6-31G* basis set. The geometric and electronic characteristics of the compounds and their total energy, normal vibration frequencies have been calculated. It has been shown that the calculated Gibbs free energies of formation for the perhydroanthracene isomerization products are in qualitative agreement with the experimental product composition of the isomerate and alkylation of adamantane with isopropyl alcohol are in qualitative agreement with the experimental composition of the products. A good agreement of calculated and experimental data on the composition of equilibrium mixtures was obtained. The theoretical geometry of the synthesized alkyladamantanes with Td symmetry very well agrees with the results of electron diffraction. Closest to the results obtained experimentally, the geometry was predicted by B3LYP, in which the lengths of C-C and C-H bonds are close to 1.544 and 1,100Ả, respectively, and the C-Csec-C and C-Cter-C angles are 109°. The results of the calculation using the B3LYP method are in good agreement with the experimental data. There is no definite relationship between the size of the molecules and the convergence of the calculated and experimental data. A practically important conclusion arising from the results of this and previous studies is that the use of the calculation method leads to “chemically accurate” data.  

Calculation of the Solubilities for 2-Aminoethyl Hydrogen Sulfate and Taurine in Water by Wilson Equation

2011 ◽  
Vol 233-235 ◽  
pp. 11-16
Author(s):  
Cai Rong Zhou ◽  
Hai Feng Wang ◽  
Xiao Hua Shi ◽  
Deng Gao Jiang
Keyword(s):  
Experimental Data ◽  
Interaction Energy ◽  
Dynamic Equilibrium ◽  
Hydrogen Sulfate ◽  
Wilson Equation ◽  
Energy Parameters ◽  
Monitoring Technique ◽  
Equilibrium Method ◽  
Laser Monitoring ◽  
Good Agreement

Using laser monitoring technique and reliable apparatus, the solubilities of both 2-aminoethyl hydrogen sulfate (AHS) and taurine in water were determined by the dynamic equilibrium method. Results of these measurements were correlated with Wilson equation separately. The solubilities calculated by the model showed good agreement with experimental data for AHS. And the interaction energy parameters of Wilson equation g12-g11 and g21-g22 correlated for binary sysytem could be used to calculate the solubilities of AHS in water. It cauld not be best using it to calculate them of taurine in water.

Algebraic study of vibrational spectra of the tetra-atomic molecules N15C12C12N15 and N14C13C13N14

2016 ◽  
Vol 15 (04) ◽  
pp. 1650036 ◽  
Author(s):  
Kamal Ziadi ◽  
Abdelhamid Bouldjedri
Keyword(s):  
Experimental Data ◽  
Potential Energy ◽  
Energy Levels ◽  
Algebraic Approach ◽  
Potential Energy Function ◽  
Vibration Modes ◽  
Bending Vibration ◽  
Dissociation Energies ◽  
Algebraic Technique ◽  
Good Agreement

In this paper, an accurate and efficient algebraic technique is used to compute linear tetra-atomic molecules stretching and bending vibration modes. Namely, several collective energy levels of linear XYYX molecules N[Formula: see text]C[Formula: see text]C[Formula: see text]N[Formula: see text] and N[Formula: see text]C[Formula: see text]C[Formula: see text]N[Formula: see text] have been described in the framework of the algebraic approach based on U[Formula: see text] Lie algebra. The results are compared to experimental data, good agreement has been obtained. The potential energy function of the two molecules is analyzed and the dissociation energies are derived.

scholarly journals Calculations of Light Scattering Matrix of Dust Aerosols for Problems of Lidar Remote Sensing

2020 ◽  
Vol 237 ◽  
pp. 08008
Author(s):  
Natalia Kustova ◽  
Alexander Konoshonkin ◽  
Anatoli Borovoi ◽  
Zhenzhu Wang ◽  
Dong Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Remote Sensing ◽  
Refractive Index ◽  
Light Scattering ◽  
Scattering Matrix ◽  
Dust Particles ◽  
Exact Methods ◽  
Particle Orientations ◽  
Crucial Parameter ◽  
Good Agreement

The light scattering matrix is calculated for large dust particles with irregular shape and refractive index of 1.3116+i0.0. The scattering matrix in the backward direction needed for lidar studies is separately discussed. In this case, the obtained results for the lidar and depolarization ratios are in good agreement with experimental data. It is shown that for randomly oriented particles the number of particle orientations needed for numerical calculations by exact methods like DDA becomes a crucial parameter. In particular, for particles with size parameters larger than 40 the number of orientations should be more than 1000.

Theoretische und experimentelle Untersuchungen zur Protonierung substituierter closo-Hexaborate -[B6H5HfacF]- und [B6H5HfacCH3]- / Theoretical and Experimental Investigations on the Protonation of Substituted closo-Hexaborates -[B6H5HfacF]- and [B6H5HfacCH3]-

1998 ◽  
Vol 53 (9) ◽  
pp. 991-996 ◽  
Author(s):  
B. Steuer ◽  
G. Peters ◽  
W. Preetz
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Boron Atom ◽  
Structural Parameters ◽  
Basis Set ◽  
Experimental Investigations ◽  
Experimentelle Untersuchungen ◽  
Good Agreement

The structural parameters and energies of the protonated compounds closo-[B6H5HfacF]- and closo-[B-H5HfacCH3]- are calculated by MP2/6-31G* optimization, as have the 1H, 11B , 13C and 19F NMR shifts using a tzp basis set and the RHF/GIAO method. The results for the octahedral molecule anions confirm the preferred localization of the additional proton in [B6H5HfacX]- in case of X = CH3 at the upper square pyramide topped by the ipso-boron atom, and in case of X = F at the lower one topped by the antipodal boron atom. The calculated NMR shifts are in good agreement with experimental data (this work). The higher BH frequencies observed for the protonated compounds as compared to the deprotonated parent clusters could be verified by ab initio frequency analyses.

Energy Levels and Electromagnetic Transition of 90-94mo Nuclei Using Ibm-1

2020 ◽  
pp. 149-152
Keyword(s):  
Experimental Data ◽  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Interacting Boson Model ◽  
Excitation Energies ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Energy States ◽  
Good Agreement

The energy states for the J , b , ɤ bands and electromagnetic transitions B (E2) values for even – even molybdenum 90 – 94 Mo nuclei are calculated in the present work of "the interacting boson model (IBM-1)" . The parameters of the equation of IBM-1 Hamiltonian are determined which yield the best excellent suit the experimental energy states . The positive parity of energy states are obtained by using IBS1. for program for even 90 – 94 Mo isotopes with bosons number 5 , 4 and 5 respectively. The" reduced transition probability B(E2)" of these neuclei are calculated and compared with the experimental data . The ratio of the excitation energies of the 41+ to 21+ states ( R4/2) are also calculated . The calculated and experimental (R4/2) values showed that the 90 – 94 Mo nuclei have the vibrational dynamical symmetry U(5). Good agreement was found from comparison between the calculated energy states and electric quadruple probabilities B(E2) transition of the 90–94Mo isotopes with the experimental data .

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