Crystal Dynamics of Rubidium. II. Anharmonic Calculations of the Phonon Self-Energy and the Heat Capacity

1973 ◽  
Vol 51 (24) ◽  
pp. 2564-2586 ◽  
Author(s):  
J. R. D. Copley
Keyword(s):  
Heat Capacity ◽  
Interatomic Potential ◽  
Thermal Strain ◽  
Large Degree ◽  
Self Energy ◽  
Lattice Heat Capacity ◽  
Crystal Dynamics ◽  
Derivatives Of ◽  
Transverse Branch ◽  
Good Agreement

We have made anharmonic calculations of phonon frequency shifts and widths, the thermal strain, and the lattice heat capacity for solid rubidium. The calculations were performed using an interatomic potential derived from the work of Price, Singwi, and Tosi. The calculated shifts are in reasonable agreement with experiment, except in the case of the Σ4 transverse branch in the [ζζ0] direction, where there are definite indications that the calculation disagrees with experiment. The calculated thermal strain is ~15% too high at intermediate temperatures. On the other hand, the calculated anharmonic contributions to the heat capacity are in good agreement with experiment at intermediate temperatures, but are 10 to 20% too low near the melting temperature. The anharmonic contributions are sensitive to the third and fourth derivatives of the potential, owing to the large degree of cancellation between the cubic and quartic terms. Furthermore there is evidence that higher order anharmonic terms may be significant.

scholarly journals Зависимость поверхностной энергии от температуры и давления для макро- и нанокристалла

2021 ◽  
Vol 63 (9) ◽  
pp. 1415
Author(s):  
М.Н. Магомедов
Keyword(s):  
High Pressures ◽  
Interatomic Potential ◽  
Nanocrystal Size ◽  
Surface Shape ◽  
Thermoelastic Properties ◽  
Specific Surface Energy ◽  
Lennard Jones ◽  
Different Temperatures ◽  
Derivatives Of ◽  
Good Agreement

Based on the RP-model of a nanocrystal, an analytical method is developed for calculating the specific surface energy (), isochoric and isobaric derivatives of the  function with respect to temperature, and isothermal derivatives of the  function with respect to pressure and density. It is shown that the method is applicable for both macro-and nanocrystals with a given number of atoms and a certain surface shape. To implement this method, the parameters of the Mie–Lennard-Jones paired interatomic potential were determined in a self-consistent way based on the thermoelastic properties of the crystal. The method was tested on macrocrystals of 15 single-component substances: for 8-FCC crystals (Cu, Ag, Au, Al, Ni, Rh, Pd, Pt) and for 7-BCC crystals (Fe, V, Nb, Ta, Cr, Mo, W). The calculations were made at different temperatures and showed good agreement with the experimental data. Using the example of FCC-Rh, the change in surface properties with a decrease of the nanocrystal size along the isotherms of 10, 300, 2000 K is studied. It is shown that at high pressures and low temperatures, there is a region where the  function increases at an isomorphic-isothermal-isobaric decrease in the nanocrystal size. As the temperature increases, this area disappears.

Development of the room temperature protocol based on room temperature ionic liquids and surfactant ionic liquids for the synthesis of derivatives of 2-amino-thiazoles and thermo-physical analysis of the synthesized derivatives using TGA-DSC.

2020 ◽  
Vol 10 ◽  
Author(s):  
Chandrakant Sarode ◽  
Sachin Yeole ◽  
Ganesh Chaudhari ◽  
Govinda Waghulde ◽  
Gaurav Gupta
Keyword(s):  
Thermal Analysis ◽  
Heat Capacity ◽  
Ionic Liquids ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Room Temperature ◽  
Heat Capacity Data ◽  
General Strategy ◽  
Capacity Data ◽  
Derivatives Of

Aims: To develop an efficient protocol, which involves an elegant exploration of the catalytic potential of both the room temperature and surfactant ionic liquids towards the synthesis of biologically important derivatives of 2-aminothiazole. Objective: Specific heat capacity data as a function of temperature for the synthesized 2- aminothiazole derivatives has been advanced by exploring their thermal profiles. Method: The thermal gravimetry analysis and differential scanning calorimetry techniques are used systematically. Results: The present strategy could prove to be a useful general strategy for researchers working in the field of surfactants and surfactant based ionic liquids towards their exploration in organic synthesis. In addition to that, effect of electronic parameters on the melting temperature of the corresponding 2-aminothiazole has been demonstrated with the help of thermal analysis. Specific heat capacity data as a function of temperature for the synthesized 2-aminothiazole derivatives has also been reported. Conclusion: Melting behavior of the synthesized 2-aminothiazole derivatives is to be described on the basis of electronic effects with the help of thermal analysis. Additionally, the specific heat capacity data can be helpful to the chemists, those are engaged in chemical modelling as well as docking studies. Furthermore, the data also helps to determine valuable thermodynamic parameters such as entropy and enthalpy.

Multicanonical Molecular Dynamics Simulation Study of the Liquid-Solid and Solid-Solid Transitions in Lennard-Jones Clusters

2011 ◽  
Author(s):  
Toshihiro Kaneko ◽  
Kenji Yasuoka ◽  
Ayori Mitsutake ◽  
Xiao Cheng Zeng
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Transition Temperature ◽  
Peak Position ◽  
Temperature Curve ◽  
Dynamics Simulation ◽  
Lennard Jones ◽  
Dynamics Simulations ◽  
First Time ◽  
Good Agreement

Multicanonical molecular dynamics simulations are applied, for the first time, to study the liquid-solid and solid-solid transitions in Lennard-Jones (LJ) clusters. The transition temperatures are estimated based on the peak position in the heat capacity versus temperature curve. For LJ31, LJ58 and LJ98, our results on the solid-solid transition temperature are in good agreement with previous ones. For LJ309, the predicted liquid-solid transition temperature is also in agreement with previous result.

The crystal dynamics of cuprous halides

1982 ◽  
Vol 60 (11) ◽  
pp. 1589-1594 ◽  
Author(s):  
Manvir S. Kushwaha
Keyword(s):  
Phonon Dispersion ◽  
Characteristic Temperature ◽  
Force Model ◽  
Phonon Dispersion Curves ◽  
Debye Characteristic Temperature ◽  
Zinc Blende ◽  
Crystal Dynamics ◽  
Bond Bending ◽  
Dynamical Description ◽  
Good Agreement

The lattice dynamics of cuprous halides have been thoroughly investigated by means of an 8-parameter bond-bending force model (BBFM), recently developed and applied successfully to study phonons in various II–VI and III–V compound semiconductors having zinc-blende (ZB) structure. The application of BBFM is made to calculate the phonon dispersion relations, phonon density of states, and temperature variation of the Debye characteristic temperature [Formula: see text] of CuCl, CuBr, and CuI. The room-temperature neutron scattering measurements for phonon dispersion curves along three principal symmetry directions and calorimetric experimental data for the Debye characteristic temperature have been used to check the validity of BBFM for the three crystals. The overall good agreement between theoretical and experimental results supports its use as an appropriate model for the dynamical description of ZB crystals.

scholarly journals Monolithic Spin Column: A New Extraction Device for Analysis of Drugs in Urine and Serum by GC/MS and HPLC/MS

2011 ◽  
Vol 94 (3) ◽  
pp. 765-774 ◽  
Author(s):  
Akira Namera ◽  
Masakata Nagao ◽  
Akihiro Nakamoto ◽  
Shota Miyazaki ◽  
Takeshi Saito
Keyword(s):  
Correlation Coefficient ◽  
Cause Of Death ◽  
Spin Column ◽  
The World ◽  
Extraction Device ◽  
Derivatizing Reagent ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of ◽  
Urine And Serum ◽  
Good Agreement

Abstract A monolithic spin column was developed for the extraction of analytes from biological materials. This column was constructed by packing a monolithic silica disk into a spin column. Sample loading, washing, and elution of the target drugs were accomplished simply by centrifugation of the column. Opiates and benzodiazepines are abused throughout the world. Identification and quantification of these drugs is very important to solve crimes or the cause of death. Three opiates (morphine, codeine, and dihydrocodeine) were extracted from urine and serum by using the column. After conversion to trimethylsilyl derivatives of the opiates by vigorous mixing with the derivatizing reagent, the solution was subjected to GC/MS. A linear curve was observed for opiates from 10 to 2500 ng/mL in urine and 5 to 1200 ng/mL in serum, respectively (correlation coefficient > 0.996). For benzodiazepines, the hydroxyl metabolites of triazolam and etizolam were extracted from urine using the column, and the eluate was directly analyzed by HPLC/MS without evaporation. The LOD values were at the ppb level, with RSD values lower than 15%. The proposed methods were successfully applied to clinical and forensic cases, and good agreement of results was obtained compared to conventional methods.

scholarly journals Direct observation of the specific heat of Majorana quasiparticles in superfluid3He-B

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yu. M. Bunkov ◽  
R. R. Gazizulin
Keyword(s):  
Heat Capacity ◽  
Low Temperatures ◽  
Condensed Matter ◽  
Direct Proof ◽  
Edge State ◽  
P Wave ◽  
Exponential Dependence ◽  
Majorana Fermions ◽  
Additional Heat ◽  
Good Agreement

AbstractThe existence of Majorana quasiparticles was predicted in the edge state in topological insulators, especially in the p-wave superfluid medium $${^3}$$ 3 He-B. Due to its purity and coherent quantum state, $${^3}$$ 3 He-B is an ideal platform for searching for Majorana fermions in condensed matter systems. In the limit of extremely low temperatures, the density of Bogolyubov quasiparticles and the heat capacity of $${^3}$$ 3 He-B decrease exponentially. In this article, we present the first observation of the deviation of its heat capacity from exponential dependence in the limit of record low cooling. We found an additional heat capacity that more than doubled the heat capacity of bulk $${^3}$$ 3 He-B and changes as T$$^2$$ 2 . The additional heat capacity is in good agreement with the predicted heat capacity of 2D gas of Majorana. This observation is a direct proof of the existence of Majorana quasiparticles in $${^3}$$ 3 He-B.

Elastic constants. II

1977 ◽  
Vol 357 (1690) ◽  
pp. 297-307
Keyword(s):  
Energy Density ◽  
Elastic Constant ◽  
Initial Stress ◽  
Elastic Constants ◽  
Interatomic Potential ◽  
Uniform Strain ◽  
Partial Derivatives ◽  
Constant Tensor ◽  
Derivatives Of

In the previous paper of this series we derived expressions for the initial stress and the elastic constant tensor for a crystal in terms of the partial derivatives of the energy density with uniform strain or sublattice displacement. In this paper we shall develop these equations further by considering the most general form of interatomic potential energies.

Bose Liquid Mean-Field Theory with Application to HeI

2019 ◽  
Vol 26 (02) ◽  
pp. 1950005
Author(s):  
Jan Maćkowiak
Keyword(s):  
Field Theory ◽  
Heat Capacity ◽  
Temperature Dependence ◽  
Mean Field Theory ◽  
Mean Field ◽  
Liquid Structure ◽  
Experimental Plot ◽  
Bose Liquid ◽  
Ordered Motion ◽  
Good Agreement

A mean-field theory is developed for a Bose liquid enclosed in a large vessel 𝒱. In accord with liquid structure concepts of Mitus et al., the liquid in 𝒱 is assumed to consist of adjacent macroscopic subregions Λk. In each subregion the bosons perform a locally ordered motion with prevailing orientation k + x, which varies randomly when passing from one subregion to another. |k| is constant, whereas temperature dependence of |x| is governed by a mean-field theory (MFT). The theory is applied to simulate HeI heat capacity CV (T) at T > Tλ = 2.17 K and CV (T) singularity at [Formula: see text]. The MFT numerical heat capacity Cn(T) = ΔE/ΔT exhibits behaviour characteristic of a singularity at [Formula: see text]: rapid increase with decreasing ΔT. Apart from [Formula: see text], good agreement of Cn(T) with CV(T) experimental plot is also found above Tλ, at T ∊ (Tλ, 3K].

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