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1.
Ronggang Tian Jiuxun Sun Wei Yang Xinying Xue Fei Yu 《Central European Journal of Physics》2008,6(3):704-710
The analytic mean-field approach (AMFP) was applied to study the thermodynamic properties of Zirconium (Zr). The analytic
expressions for the Helmholtz free energy, internal energy and equation of state have been derived. The formalism for the
case of the Morse potential is used in this work. The four potential parameters are determined by fitting the molar volume
of the three phases of Zr. The calculated molar volume of α, β and ω Zr are in fairly good agreement with the available experimental data. The results presented in this paper verify that the
AMFP is a useful approach to study the thermodynamic properties of Zr. Furthermore, we predict the variation of the relationship
of free energy and internal energy versus the molar volume at various temperatures and the dependence of the bulk modulus,
the thermal expansion coefficient and the heat capacity on temperature at zero pressure of α, β and ω Zr.
相似文献
2.
This paper provides an investigation of the phase
transition and spalling characteristic induced during shock loading
and unloading in the pure iron and the FeMnNi alloy. The impact for
the pure iron is symmetric and with same-thickness for both the
flyer and the target plate. It is found that an abnormal multiple
spalling happens in the pure iron sample as the pressure exceeds the
$\alpha -\varepsilon $ transition threshold of 13 GPa. In the
symmetric and same-thickness impact and reverse impact experiments
of the FeMnNi alloy, two abnormal tension regions occur when the
pressure exceeds the $\alpha -\varepsilon $ transition threshold of
6.3~GPa, and the reverse phase transition $\varepsilon -\alpha $
begins below 4.2~GP. The experimental process is simulated
successfully from the non-equilibrium mixture phase and Boettger's
model. Such abnormal spalling phenomena are believed to relate to
the shocked $\alpha -\varepsilon $ phase transition. The possible
reasons for the abnormal multiple spalling, which occurs during the
symmetric and same-thickness impact experiments of pure iron and
FeMnNi alloy, are discussed. 相似文献
3.
Correspondence between classical dynamics and recurrence spectra of Rydberg hydrogen atom near a metal surface 下载免费PDF全文
The chaotic behaviours of the Rydberg hydrogen atom near a metal surface are presented. A numerical comparison of Poincare surfaces of section with recurrence spectra for a few selected scaled energies indicates the correspondence between classical motion and quantum properties of an excited electron. Both results demonstrate that the scaled energy dominates sensitively the dynamical properties of system. There exists a critical scaled energy εc, for ε 〈 εc, the system is near-integrable, and as the decrease of ε the spectrum is gradually rendered regular and finally turns into a pure Coulomb field situation. On the contrary, if ε 〉 εc, with the increase of ε, the system tends to be non-integrable, the ergodic motion in phase space presages that chaotic motion appears, and more and more electrons are adsorbed on the metal surface, thus the spectrum becomes gradually simple. 相似文献
4.
Structural, thermodynamic and electronic properties of zinc-blende AlN from first-principles calculations 下载免费PDF全文
Structural, thermodynamic and electronic properties of zinc-blende
AlN under pressure are investigated by first-principles calculations
based on the plane-wave basis set. Through the analysis of enthalpy
variation of AlN in the zinc-blende (ZB) and the rock-salt (RS)
structures with pressure, we find the phase transition of AlN from
ZB to RS structure occurs at 6.7 GPa. By using the quasi-harmonic
Debye model, we obtain the heat capacity CV, Debye temperature
ΘD, Grüneisen parameter γ and thermal
expansion coefficient α. The electronic properties including
fundamental energy gaps and hydrostatic deformation potentials are
investigated and the dependence of energy gaps on pressure is
analysed. 相似文献
5.
This paper investigates the electronic structure and thermodynamic properties of LiBC in the hexagonal structure by using the generalized gradient approximation (GGA) and local density approximation correction scheme in the frame of density functional theory. The geometric structure of LiBC under zero pressure, and the dependences of the normalized lattice parameters a/ao and c/co, the ratio e/a, the normalized primitive volume V/Vo on pressure are given. The thermodynamic quantity (including the heat capacity Cv, Debye temperature 6~D, thermal expansion a and Grfineisen parameter -y) dependences on temperature and pressure are obtained through the GGA method and the quasi-harmonic Debye model. The band structures and density of state of LiBC under different pressures have also been analysed. 相似文献
6.
7.
Jun-Yao Xu Jiu-Long Chen Jun-Gang Deng Jun-Hao Cheng Hong-Ming Liu Xiao-Hua Li 《理论物理通讯》2019,71(11):1328-1334
In the present work,we predict the α decay half-lives of unknown even-even nuclei ~(296-308)120 within the two-potential approach,whose α decay energy Qa is calculated using WS3+mass model.To reduce the deviations between the predictions and experimental data due to nuclear shell effect,the analytic formula of α decay hindrance factor is introduced to the two-potential approach,whose parameters had been extracted from even-even nuclei in the region of 82 Z 126 and 152 N 184 in our previous work [Deng et al.,Chin.Phys.C 42(2018) 044102].In addition,for comparing,we use a type of α decay general formula Universal Decay Law(UDL) and a semi-empirical formula in the superheavy nucleus(SEMFLS) to calculate the half-lives of even-even nuclei ~(296-308)120.The results indicate that our predicted values and the calculated values of the above two empirical formulas are mutually confirmed.Meanwhile,we systematically study α decay chains of ~(296-308)120 and predict the decay modes for superheavy nuclei to help to identify new superheavy isotopes. 相似文献
8.
W. Yang J. X. Sun F. Yu 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(2):211-217
We present a detailed derivation of the analytic expressions for the
equation of state (EOS) and internal energy of Morse model solids based on
an analytic mean field potential (AMFP) method. The formalism is applied to
cubic boron nitride (c-BN). One set of potential parameters are determined by
fitting the experimental P-V-T data of c-BN up to 160 GPa at 295 K and 80 GPa in
the range 500–900 K. Various physical quantities including the isothermals,
thermal expansion, isochoric heat capacity, Helmholtz free energy and
internal energy are calculated and analyzed. The theoretical results are
consistent with the available experimental data and those calculated by
others. These results presented in this paper verify that the AMFP method is
a useful approach to consider the anharmonic effect at high temperature.
Numerous reasonable predictions and the change trend of the properties for
c-BN at extreme conditions have been given. 相似文献
9.
Structure and analytical potential energy function for the ground state of the BCx (x=0, -1) 下载免费PDF全文
In this paper, the electronic states of the ground states and dissociation limits of BC and BC- are correctly determined based on group theory and atomic and molecular reaction statics. The equilibrium geometries, harmonic frequencies and dissociation energies of the ground state of BC and BC- are calculated by using density function theory and quadratic CI method including single and double substitutions. The analytical potential energy functions of these states have been fitted with Murrell-Sorbie potential energy function from our ab initio calculation results. The spectroscopic data (αe, ωe and ωeχe) of each state is calculated via the relation between analytical potential energy function and spectroscopic data. All the calculations are in good agreement with the experimental data. 相似文献
10.
Calculating the dielectric anisotropy of nematic liquid crystals: a reinvestigation of the Maier——Meier
theory 下载免费PDF全文
This paper investigates the average dielectric permittivity
(\overline ε ) in the Maier--Meier theory for calculating
the dielectric anisotropy (Δε) of nematic liquid
crystals. For the reason that \overline ε of nematics
has the same expression as the dielectric permittivity of the isotropic
state, the Onsager equation for isotropic dielectric was used to
calculate it. The computed \overline ε shows reasonable
agreement with the results of the numerical methods used in the
literature. Molecular parameters, such as the polarizability and its
anisotropy, the dipole moment and its angle with the molecular long
axis, were taken from semi-empirical quantum chemistry (MOCPAC/AM1)
modeling. The calculated values of Δε according
to the Maier--Meier equation are in good agreement with the experimental
results for the investigated compounds having different core
structures and polar substituents. 相似文献
11.
First-principles investigations on elastic and thermodynamic properties of zinc-blende structure BeS 下载免费PDF全文
In this paper the elastic and thermodynamic properties of the cubic
zinc-blende structure BeS at different pressures and temperatures
are investigated by using \textit{ab initio} plane-wave
pseudopotential density functional theory method within the
generalized gradient approximation (GGA). The calculated results are
in excellent agreement with the available experimental data and
other theoretical results. It is found that the zinc-blende
structure BeS should be unstable above 60GPa. The thermodynamic
properties of the zinc-blende structure BeS are predicted by using
the quasi-harmonic Debye model. The pressure-volume-temperature
($P-V-T$) relationship, the variations of the thermal expansion
coefficient $\alpha$ and the heat capacity $C_{V}$ with pressure $P$
and temperature $T$, as well as the Gr\"{u}neisen
parameter-pressure-temperature ($\gamma -P-T$) relationship are
obtained systematically in the ranges of 0--90GPa and 0--2000K. 相似文献
12.
Investigation of analytical harmonic frequency and potential energy function,vibrational levels for the X^2∑^+ and A^2Л states of CN radical 下载免费PDF全文
This paper calculates the equilibrium structure and the potential energy functions of the ground state (X^2∑^+) and the low lying excited electronic state (A^2Л) of CN radical are calculated by using CASSCF method. The potential energy curves are obtained by a least square fitting to the modified Murrell-Sorbie function. On the basis of physical theory of potential energy function, harmonic frequency (ωe) and other spectroscopic constants (ωeχe, βe and αe) are calculated by employing the Rydberg-Klei-Rees method. The theoretical calculation results are in excellent agreement with the experimental and other complicated theoretical calculation data. In addition, the eigenvalues of vibrational levels have been calculated by solving the radial one-dimensional SchrSdinger equation of nuclear motion using the algebraic method based on the analytical potential energy function. 相似文献
13.
A critical evaluation and thermodynamic modeling for thermodynamic properties of all oxide phases and phase diagrams in the Fe–Mn–O system are presented. Optimized Gibbs energy parameters for the thermodynamic models of the oxide phases were obtained which reproduce all available and reliable experimental data within error limits from 298 K to above the liquidus temperatures at all compositions covering from known oxide phases, and oxygen partial pressure from metal saturation to 0.21 bar. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. Two spinel phases (cubic and tetragonal) were modeled using Compound Energy Formalism (CEF) with the use of physically meaningful parameters. The present Fe–Mn spinel solutions can be integrated into a larger spinel solution database, which has been already developed. The database of the model parameters can be used along with a software for Gibbs energy minimization in order to calculate any type of phase diagram section and thermodynamic properties. 相似文献
14.
The linear and nonlinear optical properties in non-centro-symmetric cubic
semiconductor GaX (X=As, Sb, P) are studied by using the first-principle
full potential linear augmented plane wave (FP-LAPW) and the linear
muffin-tin orbital (LMTO) methods. We present calculations of the
frequency-dependent complex dielectric function
and it zero-frequency limit
. A
simple scissor operator is applied to adjust the band gap from the
local-density calculations to match the experimental value. Calculations are
reported for the frequency-dependent complex second-order non-linear optical
susceptibilities
up to 6 eV and it
zero-frequency limit
. Comparison with available
experimental data shows good agreement. Our calculations show excellent
agreement between the two methods. 相似文献
15.
In-Ho Jung 《Journal of Physics and Chemistry of Solids》2004,65(10):1683-1695
A complete literature review, critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties at 1 bar total pressure of all oxide phases in the Fe-Mg-O system are presented. Optimized model equations for the thermodynamic properties of all phases are obtained which reproduce all available thermodynamic and phase equilibrium data within experimental error limits from 25 °C to above the liquidus temperatures at all compositions and oxygen partial pressures. The complex phase relationships in the system have been elucidated and discrepancies among the data have been resolved. The database of the model parameters can be used along with software for Gibbs energy minimization in order to calculate any type of phase diagram section. Sublattice models, based upon the compound energy formalism, were used for the spinel, pyroxene, olivine and monoxide phases. The use of physically reasonable models means that the models can be used to predict properties, phase equilibria, and cation site distributions in composition and temperature regions where data are not available. 相似文献
16.
《Solid State Ionics》2006,177(7-8):765-777
A complete critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties of the Mn–Cr–O system at 1 bar total pressure are presented. Optimized equations for the thermodynamic properties of all phases are obtained, which reproduce all available and reliable thermodynamic and phase equilibrium data within experimental error limits from 25 °C to above the liquidus temperatures at all compositions and oxygen partial pressures. As results of optimization, the Gibbs energy function of MnCr2O4 is for the first time properly estimated and the discrepancies of the phase diagram experiments of the Mn–Cr–O system are resolved. In particular, unexplored phase diagrams and thermodynamic properties of the Mn–Cr–O system of importance for the oxidation of SOFC interconnect are predicted on the basis of the optimized model parameters. The database of the model parameters can be used along with software for Gibbs energy minimization in order to calculate any type of phase diagram sections and thermodynamic properties. 相似文献
17.
18.
We investigate the topological properties of a trimerized parity–time(PT)symmetric non-Hermitian rhombic lattice.Although the system is PT-symmetric,the topology is not inherited from the Hermitian lattice;in contrast,the topology can be altered by the non-Hermiticity and depends on the couplings between the sublattices.The bulk–boundary correspondence is valid and the Bloch bulk captures the band topology.Topological edge states present in the two band gaps and are predicted from the global Zak phase obtained through the Wilson loop approach.In addition,the anomalous edge states compactly localize within two diamond plaquettes at the boundaries when all bands are flat at the exceptional point of the lattice.Our findings reveal the topological properties of the??PT-symmetric non-Hermitian rhombic lattice and shed light on the investigation of multi-band non-Hermitian topological phases. 相似文献
19.
X-ray diffraction study of effect of deposition conditions on α--β phase transition and stress evolution in sputter-deposited W coatings 下载免费PDF全文
Pure W and W-Cu-W trilayer coatings were deposited on an Fe substrate by d.c. magnetron sputtering. The α-β phase evolution, intragranular stress evolution in sputter-deposited W layer were investigated by x-ray diffraction. They are directly related to the film microstructure, density and adhesion. Therefore, control of the film stress and phase component transition is essential for its applications. The phase component transition from β-W to α-W and intragranular stress evolution from tensile to compressive strongly depend on the deposition parameters and can be induced by lowering Ar pressure and rising target power. The compressively stressed films with α-W phase have a dense microstructure and high adhesion to Fe substrate. 相似文献
20.
A. D'Angola G. Colonna C. Gorse M. Capitelli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):129-150
Thermodynamic and transport properties of high temperature
equilibrium air plasmas have been calculated in a wide pressure
(
atm) and temperature range (
K). The
results have been obtained by using a self-consistent approach for
the thermodynamic properties and higher order approximation of the
Chapman-Enskog method for the transport coefficients.
Debye-Hükel corrections have been considered in the
thermodynamic properties while collision integrals of charge-charge
interactions have been obtained by using a screened Coulomb
potential. Calculated values have been fitted by closed forms ready
to be inserted in fluid dynamic codes. 相似文献