Analysis Of Structural Phase Transition Research Articles

Vibrational and conformational analysis of structural phase transition in Estradiol 17β valerate with temperature

Estradiol 17β valerate (E2V) is a hormonal medicine widely used in hormone replacement therapy. E2V undergoes a reversible isosymmetric structural phase transition at low temperature (̴ 250 K) which results from the reorientation of the valerate chain. The reversible isosymmetric structural phase transition follows Ehrenfest’s classification when described as first-order and Buerger’s classification when classified as order–disorder. The conformational difference also induces changes in molecular torsional angles and on the hydrogen bond pattern. In combination with density functional theory (DFT) calculations, vibrational spectroscopy has been used to correlate the valerate chain modes with the modifications of the dihedral angles on phase transition. We are expecting improvement in our understanding of the phase transition mechanism driven by the temperature. The Conformational analysis reveals the feasible structures corresponding to changes in the dihedral angles associated with the valerate chain. The infrared spectra of calculated conformers are in good agreement with the experimental spectra of E2V structure recorded at room temperature revealing that the changes in valerate chain modes at 1115 cm−1, 1200 cm-1and 1415 cm−1 fingerprint the molecular conformation.An investigation made to determine the ligand–protein interaction of E2V through docking against estrogen receptor (ER) reveals the inhibitive and agonist nature of E2V.

Correction to: An analysis of structural phase transition and allied properties of cubic ReN and MoN compounds

Correction to: An analysis of structural phase transition and allied properties of cubic ReN and MoN compounds

An analysis of structural phase transition and allied properties of cubic ReN and MoN compounds

The present work aims at the study of structural, elastic, electronic, and thermodynamic properties of transition metal nitrides: ReN and MoN in the zinc-blende (B3) phase. The plane wave pseudopotential and norm-conserving pseudopotential have been applied in Quantum-Espresso code based on density-functional theory (DFT). The results show a first-order phase transition from B3 to B1 (rock-salt) structure at 42GPa and 2.5GPa for ReN and MoN respectively. The elastic behaviors of these compounds are also unfolded in this work. The brittleness of the ReN and ductility of MoN is identified with the help of Pugh's index and Poisson's ratio. The strong anisotropic behaviors of both compounds are detected under the influence of pressure. The electronic and bonding features of proposed compounds are evaluated by means of band structures, the density of states (DOS), Fermi surface, and charge density plots. The obtained results forecast the metallic behavior and ionic bonding of ReN and MoN in both phases: B3 and B1. Additionally, various thermodynamic properties are also investigated under high pressures and temperatures (from 0 to 2000K). Conceivably, these properties are reported for the first time in the B3 structure of these compounds and will be useful for many applications in modern technologies as well.

Theoretical and Experimental Analysis of Structural Phase Transitions for ScF[SeO3] and YF[SeO3

AbstractPhase‐pure ScF[SeO3] and YF[SeO3] were synthesized via solid‐state reactions of the corresponding rare‐earth metal sesquioxides and trifluorides with selenium dioxide in excess of fluxing cesium bromide at 700 °C for 7 d. To avoid the formation of oxosilicates, these reactions took place in corundum crucibles embedded inside of evacuated fused silica ampoules. Upon cooling down below 13 °C, a pseudo‐second‐order phase transition (P21/m → P$\bar{1}$ or P1) for ScF[SeO3] occurs, which is similar to the high‐temperature phase transition of LuF[SeO3]. By heating YF[SeO3] above 319 °C, it undergoes a first‐order phase transition (P21/c → P21/m) without passing the intermediate P$\bar{1}$ modification in contrast to LuF[SeO3]. Both the high‐temperature phase transition of YF[SeO3] and the low‐temperature phase transition of ScF[SeO3] were characterized by in‐situ X‐ray powder diffraction, X‐ray single‐crystal diffraction, thermal analysis DSC, and distortion‐mode analysis. For both cases the driving forces for the symmetry‐breaking phase transitions from the high‐ to the low‐temperature phases are discussed.

TEM Analysis of Structural Phase Transition in MBE Grown Cubic InN on MgO (001) by MBE: Effect of Hexagonal Phase Inclusion in an C-Gan Nucleation Layer

In this paper, we introduced dbcube topology for Network-on Chips(NoC). We predicted the dbcube topology has high power and low latency comparing to other topologies, and in particular mesh topology. By using xmulator simulator,we compared power and latency of this topologyto mesh topology. Finally, it is demonstrated that the network has higher power and lower latency than the mesh topology.

Symmetry considerations in structural phase transitions

The most important symmetry arguments to be considered in the analysis of structural phase transitions are reviewed. A practical approach is used, with the discussion of many examples. In particular, we stress the straightforward application of computer tools freely available in internet to solve these symmetry-related problems. We focus on programs available on the Bilbao Crystallographic Server (www.cryst.ehu.es), but also the use of some programs from the ISOTROPY site (stokes.byu.edu/isotropy.html) is discussed.

Analysis of structural phase transition of Nd 2NiO 4 + δ by scanning thermal measurement under controlled oxygen partial pressure

The dependence of the structural phase transition behavior of Nd 2NiO 4 + δ between the tetragonal and orthorhombic phases on the oxygen partial pressure, P(O 2), has been investigated by differential scanning calorimetry, DSC, and thermogravimetry and differential thermal analysis, TG-DTA. The structural phase transition temperature, T P, decreased with decreasing P(O 2), while the variations of enthalpy, Δ H, entropy, Δ S, estimated from the peak area of DSC signals and oxygen content at the phase transition, Δ δ, determined from TG curves, exhibited little dependence on P(O 2). From the relationship between T p and P(O 2), the variations of standard enthalpy, Δ H°, and entropy, Δ S°, at the phase transition have been evaluated. By considering Δ δ, Δ H° and Δ S° exhibited fair agreement with Δ H and Δ S evaluated by DSC.

Analysis of Structural Phase Transition of a Small Protein

Analysis of Structural Phase Transition of a Small Protein

AMPLIMODES: a computer program for the symmetry-mode analysis of structural phase transitions

AMPLIMODES: a computer program for the symmetry-mode analysis of structural phase transitions

Symmetrical Analysis of Structural Phase Transitions in Crystals with the O h 5 Space Group

Using the group-theoretical methods, the complete set of critical and noncritical order parameters arising at phase transitions in crystals with the Oh 5 - Fm3m space group has been obtained and analyzed. The mechanical and permutation representations have been constructed, and their composition for all the right systems of points of the Oh 5 space group has been determined. Experimental data on structural phase transitions in ammonium cryolites and elpasolites have been considered.

On shear-induced phase transitions in perfect crystals

This is an analysis of structural phase transitions in b.c.t. crystals controlled by tensile loading along a crystallographic axis.

Analysis of structural phase transitions by computer simulation

This paper presents the results from molecular-dynamics calculations on a lattice-dynamical system which undergoes a structural phase transition. The characteristics of the model system used for the calculations are described in detail; the model is two dimensional, has an antiferro-distortive structural change, and is in the category of displacive structural transitions. The following results are obtained from the molecular-dynamics calculations. First, some equilibrium properties are shown, including the static correlation function, to establish that the system has a second-order phase transition. Second, the results for the time-dependent order parameter or soft-mode correlation function are given. Near the transition the spectral function for this correlation function exhibits a very narrow and intense central peak, in addition to the soft-mode peak. The temperature dependences of the soft-mode frequency and the central-peak width are given. The results obtained here are very similar to experimental observations, particularly on SrTi${\mathrm{O}}_{3}$, and they are used to argue that only intrinsic anharmonic mechanisms are needed to explain the origin of central peaks. Third, extensive results are given for the temperature and wave-vector dependence of the displacement correlation function, which give the wave-vector dependence of the central-peak characteristics. In a small temperature interval around the transition and in a small region of wave-vector space around but not including the soft-mode wave vector, the central peak is found to split so that the maximum is not exactly at zero frequency. Lastly, results for the energy-density correlation function are given for wave vectors around the soft-mode wave vector and for temperatures above the transition. Near the transition the corresponding spectral function is found to develop a pronounced high-frequency peak.