scholarly journals High-pressure study of thermodynamic parameters of diamond-type structured crystals using interatomic Morse potentials

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
Duc Ba Nguyen ◽  
Hiep Phi Trinh
Keyword(s):  
High Pressure ◽  
Thermodynamic Parameters ◽  
Relative Displacement ◽  
The Mean ◽  
Experimental Values ◽  
X Ray Absorption ◽  
Potential Parameters ◽  
Diamond Type ◽  
High Pressure Study ◽  
Morse Potentials

AbstractIn this work, we have determined the mean square relative displacement, elastic constant, anharmonic effective potential, correlated function, local force constant, and other thermodynamic parameters of diamond-type structured crystals under high-pressure up to 14 GPa. The parameters are calculated through theoretical interatomic Morse potential parameters, by using the sublimation energy, the compressibility, and the lattice constant in the expanded X-ray absorption fine structure spectrum. Numerical results agree well with the experimental values and other theories.

scholarly journals Determination Morse Potential Parameters by the Theoretical Method in EXAFS

2021 ◽  
Author(s):  
Nguyen Ba Duc ◽  
Trinh Phi Hiep ◽  
Nguyen Thu
Keyword(s):  
Morse Potential ◽  
Theoretical Method ◽  
Relative Displacement ◽  
Face Centered Cubic ◽  
Effective Parameters ◽  
Face Centered ◽  
Silicon And Germanium ◽  
Experimental Values ◽  
X Ray Absorption ◽  
Potential Parameters

Abstract A new method for estimating Morse potential's effective parameters has developed using the sublimation energy, the compressibility, and the lattice constant in expanded X-ray absorption fine structure spectra. Application the received parameters of Morse potential to calculate the mean square relative displacement, elastic constant, anharmonic effective potential, correlated function, and local force constant for diamond-type structure crystals such as silicon and germanium crystals, and face-centered cubic crystals as copper, silver. Numerical results agree well with the experimental values and other theories.

High-pressure study ofα-quartzGeO2using extended x-ray-absorption fine structure

1988 ◽  
Vol 37 (11) ◽  
pp. 6513-6516 ◽  
Author(s):  
B. Houser ◽  
N. Alberding ◽  
R. Ingalls ◽  
E. D. Crozier
Keyword(s):  
High Pressure ◽  
Fine Structure ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
High Pressure Study

DFT Benchmark Study of the O--O Bond Dissociation Energy in Peroxides Validated with High-Level Ab-Initio Calculations

2019 ◽  
Author(s):  
Danilo Carmona ◽  
Pablo Jaque ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Reference Value ◽  
Basis Set ◽  
Basis Sets ◽  
Mean Deviation ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
The Mean ◽  
Experimental Values ◽  
High Level ◽  
Almost All

<div><div><div><p>Peroxides play a central role in many chemical and biological pro- cesses such as the Fenton reaction. The relevance of these compounds lies in the low stability of the O–O bond which upon dissociation results in radical species able to initiate various chemical or biological processes. In this work, a set of 64 DFT functional-basis set combinations has been validated in terms of their capability to describe bond dissociation energies (BDE) for the O–O bond in a database of 14 ROOH peroxides for which experimental values ofBDE are available. Moreover, the electronic contributions to the BDE were obtained for four of the peroxides and the anion H2O2− at the CBS limit at CCSD(T) level with Dunning’s basis sets up to triple–ζ quality provid- ing a reference value for the hydrogen peroxide anion as a model. Almost all the functionals considered here yielded mean absolute deviations around 5.0 kcal mol−1. The smallest values were observed for the ωB97 family and the Minnesota M11 functional with a marked basis set dependence. Despite the mean deviation, order relations among BDE experimental values of peroxides were also considered. The ωB97 family was able to reproduce the relations correctly whereas other functionals presented a marked dependence on the chemical nature of the R group. Interestingly, M11 functional did not show a very good agreement with the established order despite its good performance in the mean error. The obtained results support the use of similar validation strategies for proper prediction of BDE or other molecular properties by DF Tmethods in subsequent related studies.</p></div></div></div>

High Pressure Studies of Quantum Well Emission and Deep Emission in GaInP(ordered)-GaAs Heterostructures

1997 ◽  
Vol 499 ◽  
Author(s):  
S. H. Kwok ◽  
P. Y. Yu ◽  
K. Uchida ◽  
T. Arai
Keyword(s):  
High Pressure ◽  
Quantum Well ◽  
Emission Band ◽  
Excitation Power ◽  
High Excitation ◽  
High Pressure Studies ◽  
Band Alignments ◽  
High Pressure Study

ABSTRACTWe report on a high pressure study of emission from a series of GaInP(ordered)/GaAs heterostructures. A so-called “deep emission” band at 1.46 eV is observed in all our samples. At high excitation power, quantum well emission emerges in only one structure where thin GaP layers are inserted on both sides of the GaAs well. From the pressure dependent emission in this sample we have determined its band alignments. The role of the GaP layers in suppressing the deep emission is elucidated.

X-ray absorption study of Cu, Zn SOD under high pressure

2000 ◽  
Vol 19 (1-6) ◽  
pp. 277-283 ◽  
Author(s):  
Isabella Ascone ◽  
Andrea Cognigni ◽  
Yann Le Godec ◽  
Jean Paul Itié
Keyword(s):  
High Pressure ◽  
Absorption Study ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Ro-vibrational energies of cesium dimer and lithium dimer with molecular attractive potential

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. A. Onate ◽  
T. A. Akanbi ◽  
I. B. Okon
Keyword(s):  
Thermal Properties ◽  
Attractive Potential ◽  
Average Deviation ◽  
Radial Wave ◽  
Lithium Dimer ◽  
Temperature Parameter ◽  
Vibrational Energies ◽  
Experimental Values ◽  
Uvarov Method ◽  
Potential Parameters

AbstractAn approximate solution of the Schrӧdinger equation for a molecular attractive potential was obtained using the parametric Nikiforov–Uvarov method. The energy equation and the corresponding radial wave functions were calculated. The effects of the potential parameters on the energy eigenvalues were examined. The thermal properties under the molecular attractive potential were calculated and the behaviour of the thermal properties with the maximum quantum state (λ) and the temperature parameter (β) respectively, were studied. Using the molecular spectroscopic parameters, the Rydberg–Klein–Rees (RKR) of cesium dimer and lithium dimer were both obtained and compared with the experimental values. The RKR values of both cesium dimer and lithium dimer calculated aligned with the observed values. The deviation and average deviation of the RKR for each molecule were also calculated.

Halogens molecular modifications with high pressure: the case of iodine

2021 ◽  
Author(s):  
Jingming Shi ◽  
Emiliano Fonda ◽  
Silvana Botti ◽  
Miguel A. L. Marques ◽  
Toru Shinmei ◽  
...  
Keyword(s):  
High Pressure ◽  
Absorption Spectroscopy ◽  
Diatomic Molecules ◽  
Giant Planets ◽  
Atomistic Modeling ◽  
X Ray ◽  
X Ray Absorption

Metallization and dissociation are key transformations in diatomic molecules at high densities particularly significant for modeling giant planets. Using X-ray absorption spectroscopy and atomistic modeling, we demonstrate that in halogens,...

High-Pressure Study of Metallocenes, M(η5-C5H5)2(M = Fe, Co)

2007 ◽  
Vol 76 (Suppl.A) ◽  
pp. 31-32
Author(s):  
Sergey V. Ovsyannikov ◽  
Vladimir V. Shchennikov ◽  
Alexander N. Titov ◽  
Yoshiya Uwatoko
Keyword(s):  
High Pressure ◽  
High Pressure Study

In-situ high-pressure study of the ordered phase of ethyl propionate

2007 ◽  
Vol 63 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Roman Gajda ◽  
Andrzej Katrusiak
Keyword(s):  
High Pressure ◽  
Degrees Of Freedom ◽  
Molecular Volume ◽  
Ethyl Propionate ◽  
Intermolecular Contacts ◽  
High Pressure Study ◽  
Pressure Phase ◽  
Three Degrees Of Freedom ◽  
Volume Difference

Ethyl propionate, C5H10O2 (m.p. 199 K), has been in-situ pressure-frozen and its structure determined at 1.34, 1.98 and 2.45 GPa. The crystal structure of the new high-pressure phase (denoted β) is different from phase α obtained by lowering the temperature. The freezing pressure of ethyl propionate at 296 K is 1.03 GPa. The molecule assumes an extended chain s-trans–trans–trans conformation, only slightly distorted from planarity. The closest intermolecular contacts in both phases are formed between carbonyl O and methyl H atoms; however, the ethyl-group H atoms in phase β form no contacts shorter than 2.58 Å. A considerable molecular volume difference of 24.2 Å3 between phases α and β can be rationalized in terms of degrees of freedom of molecules arranged into closely packed structures: the three degrees of freedom allowed for rearrangements of molecules confined to planar sheets in phase α, but are not sufficient for obtaining a densely packed pattern.

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