Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

scholarly journals THE METHOD OF INCREMENTS — A WAVEFUNCTION-BASED AB-INITIO CORRELATION METHOD FOR SOLIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2204-2214 ◽  
Author(s):  
BEATE PAULUS
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ground State ◽  
Infinite System ◽  
Correlation Energy ◽  
Correlation Method ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Good Agreement

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

Calculating Fundamental Vibrational Frequencies of Rutile by Combining Ab Initio Method with GF Matrix Method

1994 ◽  
Vol 05 (02) ◽  
pp. 299-301
Author(s):  
Lin Libin ◽  
Zheng Xiangyin
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Matrix Method ◽  
Cluster Model ◽  
Normal Modes ◽  
Vibrational Frequencies ◽  
Ab Initio Method ◽  
Environment Factor ◽  
Factor Α ◽  
Good Agreement

Based on cluster model, we have calculated the fundamental vibrational frequencies of rutile by combining ab initio method and Wilson’s GF-matrix method. In the calculation, we have introduced the concept of environment factor α to correct the force field of the cluster model. The results of calculation are in good agreement to the experimental data and the normal modes give us clear physical picture of the crystal vibration.

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.

THE STATIC DIELECTRIC CONSTANT OF NaCl, KCl, AND KBr AT TEMPERATURES BETWEEN 4.2 °K AND 300 °K

1966 ◽  
Vol 44 (10) ◽  
pp. 2211-2230 ◽  
Author(s):  
M. C. Robinson ◽  
A. C. Hollis Hallett
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Debye Temperature ◽  
Relative Error ◽  
Low Temperatures ◽  
Absolute Error ◽  
Static Dielectric Constant ◽  
Good Agreement

Measurements of the static dielectric constant, εst, were made, using a transformer bridge with an absolute error of about 0.5% and a relative error of less than 0.02%. At 300 °K, the values obtained for εst were 5.90, 4.81, and 4.88, while 104(1/εst)(∂εst/∂T)p, was found to be 3.21, 2.93, and 3.10 (°K)−1 for NaCl, KCl, and KBr respectively, in good agreement with other recent measurements.At low temperatures, the curve of εst versus temperature was found to show a minimum, but it has not been found possible to explain all of the observed increase in εst with decreasing temperature below the minimum by the presence of impurities.The variation of εst with temperature is analyzed in detail on the basis of the evaluation made by Szigeti of the anharmonic contribution, G, to the dielectric constant. Estimates of (∂εst/∂T)v, which is equal to (∂G/∂T)v according to Szigeti (1961), have been made from the experimental data, and the curves of (∂εst/∂T)v versus temperature show an unexpected maximum at a temperature near θD/4,where θD is the Debye temperature.

Comparative Study on the Effective Dielectric Constant of the Graded Composites

2013 ◽  
Vol 677 ◽  
pp. 192-196
Author(s):  
Chun Zhen Fan ◽  
Jun Qiao Wang ◽  
Er Jun Liang
Keyword(s):  
Dielectric Constant ◽  
Approximation Method ◽  
Dipole Approximation ◽  
Effective Dielectric Constant ◽  
Gradual Transition ◽  
Sum Rule ◽  
Number Of Layers ◽  
Continuous Band ◽  
Rule Method ◽  
Good Agreement

The effective dielectric constant of the graded composites was calculated with three different methods, namely, the nonlinear differential effective dipole approximation method (NDEDA), the Maxwell-Garnette method (MGT) and the sum rule method (Sum). In each layer of the graded composites, the distribution of the dielectric constant follows a Drude form. Our numerical results show that when the number of layers N inside the graded composites increases, a gradual transition from sharp peaks to an emerging broad continuous band is clearly obtained. Moreover, the results obtained by the MGT and sum rule methods achieve a good agreement with that by the NDEDA method when N is approaching infinity.

Nitrosyl cyanide and related aspects of the ONCN potential surface

1978 ◽  
Vol 31 (11) ◽  
pp. 2349 ◽  
Author(s):  
BG Gowenlock ◽  
L Radom
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Related Species ◽  
Potential Surface ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Hartree Fock ◽  
Split Valence ◽  
Good Agreement

Ab initio molecular orbital calculations using the restricted Hartree-Fock approach have been carried out for nitrosyl cyanide and related species on the ONCN potential surface. Full geometry optimizations have been performed with the minimal STO-3G and split-valence 4-31G basis sets. Calculated (4-31G) geometries are in good agreement with available experimental data as are the energy changes in the reactions ONCN → NO + CN and NO + CN → N2 + CO. Possible mechanisms are discussed.

scholarly journals Nitrogen Dissolution in Liquid Ga and Fe: Comprehensive Ab Initio Analysis, Relevance for Crystallization of GaN

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1306
Author(s):  
Jacek Piechota ◽  
Stanislaw Krukowski ◽  
Petro Sadovyi ◽  
Bohdan Sadovyi ◽  
Sylwester Porowski ◽  
...  
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Potential ◽  
Nitrogen Solubility ◽  
Molecular Nitrogen ◽  
Ideal Gas ◽  
The Difference ◽  
Good Agreement

The dissolution of molecular nitrogen in Ga and Fe was investigated by ab initio calculations and some complementary experiments. It was found that the N bonding inside these solvents is fundamentally different. For Ga, it is between Ga4s and Ga4p and N2p states whereas for Fe this is by N2p to Fe4s, Fe4p and Fe3d states. Accordingly, the energy of dissolution of N2 for arbitrarily chosen starting atomic configurations was 0.535 eV/mol and −0.299 eV/mol for Ga and Fe, respectively. For configurations optimized with molecular dynamics, the difference between the corresponding energy values, 1.107 eV/mol and 0.003 eV/mol, was similarly large. Full thermodynamic analysis of chemical potential was made employing entropy-derived terms in a Debye picture. The entropy-dependent terms were obtained via a normal conditions path to avoid singularity of ideal gas entropy at zero K. Nitrogen solubility as a function of temperature and N2 pressure was evaluated, being much higher for Fe than for Ga. For T=1800 K and p=104 bar, the N concentration in Ga was 3×10−3 at. fr. whereas for Fe, it was 9×10−2 at. fr. in very good agreement with experimental data. It indicates that liquid Fe could be a prospective solvent for GaN crystallization from metallic solutions.

scholarly journals Ab initio studies of O<sub>2</sub><sup>−</sup>(H<sub>2</sub>O)<sub><i>n</i></sub> and O<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub><i>n</i></sub> anionic molecular clusters, <i>n</i>≤12

2011 ◽  
Vol 11 (5) ◽  
pp. 13947-13973 ◽  
Author(s):  
N. Bork ◽  
T. Kurtén ◽  
M. B. Enghoff ◽  
J. O. P. Pedersen ◽  
K. V. Mikkelsen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Molecular Clusters ◽  
Water Molecules ◽  
Cluster Growth ◽  
Excess Charge ◽  
Atmospheric Conditions ◽  
Ab Initio Study ◽  
Normal Hydrogen ◽  
Good Agreement

Abstract. An ab initio study of gaseous clusters of O2− and O2− with water is presented. Based on thorough scans of configurational space, we determine the thermodynamics of cluster growth. The results are in good agreement with benchmark computational methods and existing experimental data. We find that anionic O2−(H2O)n and O3−(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding. Although clustering up to 12 H2O, we find that the O2 and O3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O2− and O3− speicies are thus accessible for further reactions. Finally, the thermodynamics of a few relevant cluster reactions are considered.

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