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Articles 29611 - 29640 of 36684

Full-Text Articles in Physical Sciences and Mathematics

Computation Of Overlap, Kinetic And Nuclear Attraction Integrals By A Novel Method, Gökhan Budak, Abdulhali̇k Karabulut, Lütfü Demi̇r, Nagi̇f Sefteroğlu Nabi̇yev, Yusuf Şahi̇n Jan 2001

Computation Of Overlap, Kinetic And Nuclear Attraction Integrals By A Novel Method, Gökhan Budak, Abdulhali̇k Karabulut, Lütfü Demi̇r, Nagi̇f Sefteroğlu Nabi̇yev, Yusuf Şahi̇n

Turkish Journal of Physics

A new way of computing overlap, kinetic and nuclear attraction integrals over Slater functions by means of optimized Gaussian expansion is proposed. This article is concerned with the construction of the general algorithm for evaluating the three integrals. These integral formulae presented in the form of a series whose terms are the analytical function of inter-atomic distances. In the present method, unlike many other popular methods, the numerical integration procedure is unnecessary since it does not contain the incomplete gamma function. The present scheme has been programmed in standard Fortran-77 and tested for various orbitals. The result of the calculation …

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Some String Cosmological Models In Cylindrically Symmetric Inhomogeneous Universe, Hüsnü Baysal, İlhami̇ Yavuz, İsmai̇l Tarhan, Uğur Camci, İshan Yilmaz Jan 2001

Some String Cosmological Models In Cylindrically Symmetric Inhomogeneous Universe, Hüsnü Baysal, İlhami̇ Yavuz, İsmai̇l Tarhan, Uğur Camci, İshan Yilmaz

Turkish Journal of Physics

The aim of this paper is to investigate the behavior of a string in the cylindrically symmetric inhomogeneous cosmological model. It has been assumed that expansion \theta in the model is proportional to \sigma^1_1 of the eigenvalue of the shear tensor \sigma^{\mu}_{\nu}. Also, various physical and geometrical properties of the model have been discussed.

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Lattice Dynamical Calculations For The Co-Fe Alloys, Kemal Çolakoğlu, Yasemi̇n Özteki̇n Çi̇ftçi̇ Jan 2001

Lattice Dynamical Calculations For The Co-Fe Alloys, Kemal Çolakoğlu, Yasemi̇n Özteki̇n Çi̇ftçi̇

Turkish Journal of Physics

Lattice dynamical calculations are performed on Co_{0.92}-Fe_{0.08} alloy with fcc structure. The de Launay Angular force (DAF) model is used to represent the ion-ion intreactions, and the long-range ion-electron interactions are accounted for along the lines of the Sharma-Joshi scheme. The frequency distribution and the lattice specific heat are also computed for the studied alloys. The present theoretical results are in reasonable agreement with the available experimental data.

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Second Order Elastic Constants And Some Thermoelastic Properties Of Alkali Halides Using Woodcock Potential, Harun Reşi̇t Yazar, Sedat Ağan, Kemal Çolakoğlu Jan 2001

Second Order Elastic Constants And Some Thermoelastic Properties Of Alkali Halides Using Woodcock Potential, Harun Reşi̇t Yazar, Sedat Ağan, Kemal Çolakoğlu

Turkish Journal of Physics

Second Order Elastic Constants (S.O.E.C) of NaCl-type crystals have been calculated using the Woodcock potential. Short-range repulsive interactions have been included up to second-nearest neighbors. This potential form represents the composite form of the inverse power dependence and exponential dependence of the repulsive energy on interionic distance. Some thermoelastic and thermodynamic properties such as Anderson-Grüneisen parameters \delta _{T}, and \delta _{S}, Volume thermal expansion coefficient \beta and Grüneisen gama \gamma _{G} have been calculated in terms of calculated values of S.O.E.C and Third Order Elastic Constant ( T.O.E.C).

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The Lattice Dynamics And The Elastic Behaviour Of Fcc And Bcc Ba, Yasemi̇n Özteki̇n Çi̇ftçi̇, Kemal Çolakoğlu Jan 2001

The Lattice Dynamics And The Elastic Behaviour Of Fcc And Bcc Ba, Yasemi̇n Özteki̇n Çi̇ftçi̇, Kemal Çolakoğlu

Turkish Journal of Physics

The two-body pairwise E.G.E.P. (Extended Generalized Exponantial Potential) type Morse potential and volume dependent energy are assumed to represent the total energy of the Ba crystal. The parametrized potential is used to calculate the second- and third-order elastic constants C_{ij} and C_{ijk}, pressure derivatives of bulk moduli and Grüneisen parameter \gamma . The phonon frequencies are also computed and plotted. The obtained results are compared with available experimental data and, in general, the agreement is good.

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Iba-1 Calculations Of E2/M1 Mixing Ratios And Quadrupole Moments In ^{154}Gd, Mehmet Baylan Jan 2001

Iba-1 Calculations Of E2/M1 Mixing Ratios And Quadrupole Moments In ^{154}Gd, Mehmet Baylan

Turkish Journal of Physics

In this study the Interacting Boson Approximation is applied in its basic form (IBA-1) to the calculation of gamma-ray E2/M1 multipole mixing ratios and quadrupole moments [Q( 2^{+} )] of electromagnetic transitions in ^{154}Gd. The numerical results obtained for ^{154}Gd are in reasanably good agreement with previous experimental and theoretical values.

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Built-In Potential Measurements In A-Si:H P-I-N Solar Cells, Ruhi̇ Kaplan, Bengü Kaplan Jan 2001

Built-In Potential Measurements In A-Si:H P-I-N Solar Cells, Ruhi̇ Kaplan, Bengü Kaplan

Turkish Journal of Physics

We have measured the open-circuit voltage V_{oc} and the short-circuit current density J_{sc} of amorphous silicon (a-Si:H) p-i-n solar cells deposited by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at different monochromatic illuminations, and temperatures. From the measurements, the built-in potential V_{bi} was determined by using two different methods: activation energy and differential temperature. The results from both methods were analyzed and compared as a function of excitation wavelength. It was observed that there is good agreement between the two methods. We found that V_{bi} increases until about 650 nm, and then decreases with increasing wavelength. This behaviour is explained and …

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Space Charge Limited Current At High Fields In Al-Ge-Al Surface Barrier Devices, A. I. Mukolu Jan 2001

Space Charge Limited Current At High Fields In Al-Ge-Al Surface Barrier Devices, A. I. Mukolu

Turkish Journal of Physics

The current-voltage (I-V) characteristics of Aluminium-Germanium-Aluminium (Al-Ge-Al) surface barrier devices at different fields (

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Coproduct Of Su_{Q} (2), Coherent States And Four Point Function With Logarithmic Regge Trajectories, M. Arik, Ayşe Peker-Dobie Jan 2001

Coproduct Of Su_{Q} (2), Coherent States And Four Point Function With Logarithmic Regge Trajectories, M. Arik, Ayşe Peker-Dobie

Turkish Journal of Physics

The representation of the operators belonging to a 2 \times 2 SU_q (2) matrix yield a Hilbert space H. The coproducts of these operators define a Hilbert space H^{(2)} isomorphic to H and canonically embedded in H \otimes H. The four-point function obtained by taking the scalar product of the ground state of H^{(2)} with the coherent states in H \otimes H is uniquely defined, is meromorphic and has Regge behaviour.

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On The Evaluation Of Determinantal Wave Functions In Open-Shell Hartree-Fock Theory, I. I. Guseinov, Ramazan Demi̇r Jan 2001

On The Evaluation Of Determinantal Wave Functions In Open-Shell Hartree-Fock Theory, I. I. Guseinov, Ramazan Demi̇r

Turkish Journal of Physics

Slater method is modified for the evaluation of determinantal wave functions appearing in open-shell Hartree-Fock (HF) theory [1]. Using modified Slater method we have calculated, as an example, the orbital energies and the wave functions of terms obtained from the electronic configuration of a ground state of an N-atom system in the Hartree-Fock-Roothaan (HFR) approximation. The modified determinantal method introduced in this paper can be of considerable help and importance in the simplification and calculation of atomic and molecular electronic structure.

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Excitation Plus Ionization In Electron-Atom Collisions To He^{+} (N=2): (E,2e), (E, E\Gamma ) And (E, 2e\Gamma ) Studies, Mevlut Dogan, Albert Crowe Jan 2001

Excitation Plus Ionization In Electron-Atom Collisions To He^{+} (N=2): (E,2e), (E, E\Gamma ) And (E, 2e\Gamma ) Studies, Mevlut Dogan, Albert Crowe

Turkish Journal of Physics

Simultaneous excitation-ionization of helium atoms by electron impact is observed by the coincidence detection of the outgoing particles. The relationship between (e,2e), (e,e\gamma ) and (e,2e\gamma ) experiments is discussed.

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Covariant Two Fermion Equations With Anomalous Moments, Ahmet Turan Alan, Z. Zekeri̇ya Aydin, Nuretti̇n Karagöz, Ali̇ Ulvi̇ Yilmazer Jan 2001

Covariant Two Fermion Equations With Anomalous Moments, Ahmet Turan Alan, Z. Zekeri̇ya Aydin, Nuretti̇n Karagöz, Ali̇ Ulvi̇ Yilmazer

Turkish Journal of Physics

We derive covariant equations for two-fermion systems, taking into account the anomalous magnetic moments of the particles.

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Double Transition Effect In Anderson Transition, Hüseyi̇n Aktaş Jan 2001

Double Transition Effect In Anderson Transition, Hüseyi̇n Aktaş

Turkish Journal of Physics

In this work we have studied the electronic mobility \mu within a completely disordered lattice system by using the strong interatomic hopping potential V(r) = ( - {\frac{{r}}{{a_{o}} }}) \exp( - r / a_{o} ) for site representation of the Hamiltonian. It is shown that a metallic system of a completely disordered lattice first goes insulating and then goes back to metallic again at higher atomic density \rho .

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Autoionization Resonances In The Simultaneous Excitation-Ionization Of Helium, Mevlut Dogan, Albert Crowe Jan 2001

Autoionization Resonances In The Simultaneous Excitation-Ionization Of Helium, Mevlut Dogan, Albert Crowe

Turkish Journal of Physics

The effect of autoionizing states on excitation-ionization processes has been investigated experimentally by observation of the electron impact ionization process leading to He^{ + }(2p) with the excitation energy region in helium corresponding to doubly excitated states above the second ionization threshold. Also, the process arising from the decay of the doubly excited `parity unfavoured' (2p^{2})^{3}P state of helium, is studied.

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The Langmuir Properties Of A Mixed Copolysiloxane Monolayer, Rifat Çapan, Tim H. Richardson, David Lacey Jan 2001

The Langmuir Properties Of A Mixed Copolysiloxane Monolayer, Rifat Çapan, Tim H. Richardson, David Lacey

Turkish Journal of Physics

A family of linear copolysiloxanes [1-3] substituted with side chains containing carboxylic head groups has been synthesised. The Langmuir properties of the mixed monolayer at the water-air interface has been studied using a single layer Langmuir trough. The area per molecule for the mixed monolayer is calculated theoretically and experimentally. This study has not only shown that there is an excellent agreement between theoretical and experimental values, but has also shown that this mixed monolayer at the water-air interface can be transferred as a monolayer onto a solid substrate.

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Magnetization Measurements On Electrodeposited Cu_{1 - X}Co_{X} Alloy Films, Ömer F. Bakkaloğlu, İsmai̇l H. Karahan, Hasan Efeoğlu, Muhammet Yildirim, Uğur Çevi̇k, Yahya Kemal Yoğurtçu Jan 2001

Magnetization Measurements On Electrodeposited Cu_{1 - X}Co_{X} Alloy Films, Ömer F. Bakkaloğlu, İsmai̇l H. Karahan, Hasan Efeoğlu, Muhammet Yildirim, Uğur Çevi̇k, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

The magnetic properties of Cu_{1 - x}Co_{x} alloy films prepared by electrodeposition technique were investigated by Alternating Gradient Force Magnetometer. The magnetization curves of Cu_{0.94}Co_{0.06}, Cu_{0.87}Co_{0.13} and Cu_{0.74}Co_{0.26} films were easily saturated while the other Cu_{1 - x}Co_{x} samples with x= 0.17, 0.19 and 0.21 had more inclined magnetization curves. The saturation magnetization value of Cu_{1 - x}Co_{x} film increased with increasing Co content in the film. The minimum values of the ratio of remanence to magnetization and the coercive field were determined in the Cu_{0.81}Co_{0.19} alloy film among the others. The ferromagnetic order in the Cu_{1 - x}Co_{x} films …

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Production And Structure Of Rapidly Solidified Al-Si Alloys, Orhan Uzun, Tuncay Karaaslan, Mustafa Keski̇n Jan 2001

Production And Structure Of Rapidly Solidified Al-Si Alloys, Orhan Uzun, Tuncay Karaaslan, Mustafa Keski̇n

Turkish Journal of Physics

Al-Si alloys with compositions 8, 12, 16wt% Si were manufactured by chill casting and melt-spinning (MS) methods. The resulting ribbon samples have been characterized by optical and scanning electron microscopy (SEM) and X-ray diffractometry and compared with their ingot counterparts. Microstructural examinations revealed that microstructures of the melt-spun ribbons were quite fine compared to their ingot counterparts. Both XRD analyses and microstructural examinations indicated that the solubility of Si in \alpha -Al phase was nearly complete.

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Lattice Changes In Shape Memory Cuznal Alloys On Aging At Room Temperature, Seyfetti̇n Çakmak, Ekrem Artunç, Nejdet Kayali, Osman Adigüzel Jan 2001

Lattice Changes In Shape Memory Cuznal Alloys On Aging At Room Temperature, Seyfetti̇n Çakmak, Ekrem Artunç, Nejdet Kayali, Osman Adigüzel

Turkish Journal of Physics

The aging behavior of CuZnAl martensites (Cu-21.62 wt.% Zn-5.68 wt.% Al and Cu-24.98 wt.% Zn-4.43 wt.% Al) at about 297 K was studied by analyzing diffraction line profiles obtained by X-ray diffractometry. For the alloys, the change of the lattice parameters and the tetragonality associated with the aging time at room temperature were investigated. The habit planes versus the aging time at room temperature were calculated using the De Vos-Aernoundt-Delaey model, based on the crystallographic theory of Wechsler-Lieberman-Read(WLR), and from the DO_{3}\rightarrow 18R martensite transformation theory.

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Physical Properties Of Melt-Cast Annealed Bi_{1.6}Pb_{0.4}Sr_{2}Ca_{3}Cu_{4} O_{12} Compound, Ati̇lla Coşkun, Beki̇r Özçeli̇k, Keri̇m Kiymaç Jan 2001

Physical Properties Of Melt-Cast Annealed Bi_{1.6}Pb_{0.4}Sr_{2}Ca_{3}Cu_{4} O_{12} Compound, Ati̇lla Coşkun, Beki̇r Özçeli̇k, Keri̇m Kiymaç

Turkish Journal of Physics

A Bi_{1.6}Pb_{0.4}Sr_{2}Ca_{3}Cu_{4}O_{12} compound was produced by melt-casting method. The microstructure of the sample was studied by Scanning Electron Microscopy. Phase analysis was carried out by X-ray diffraction patterns and EDAX. The electrical resistance exhibites the existance of a superconducting phase with an onset temperature T_{c} at 110 K along with a minor phase with an onset T_{c} at 80 K. It has been found that the superconducting phase temperature T_{c} increases with increasing sintering temperature.

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Measurement Of Dσ/Dy For High Mass Drell-Yan E+E- Pairs From Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2001

Measurement Of Dσ/Dy For High Mass Drell-Yan E+E- Pairs From Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on the first measurement of the rapidity distribution dσ/dy over nearly the entire kinematic region of rapidity for e+e- pairs in both the Z-boson region of 66<Mee/c2 and in the high mass region of Mee>116 GeV/c2. The data sample consists of 108 pb-1 of pp̅ collisions at √s =1.8 TeV taken by the Collider Detector at Fermilab during 1992–1995. The total cross section in the Z-boson region is measured to be 252±11 pb. The measured total cross section and dσ/dy are compared …

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Multiple Structures Of (110) Csl Twist Boundaries In Fcc Metals, A. Ghafoor, B. A. S. Faridi, S. A. Ahmad Jan 2001

Multiple Structures Of (110) Csl Twist Boundaries In Fcc Metals, A. Ghafoor, B. A. S. Faridi, S. A. Ahmad

Turkish Journal of Physics

The geometry of different possible structures of (110) fcc twist boundaries is explored. Computer simulation of all possible low energy structures have been carried out for \Sigma=3 and \Sigma=9 twist boundaries using many-body potentials representing copper, silver and gold. Low symmetry structures are found to have lower energies than the high symmetry CSL structures.

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Multiparticle Equations For Scalar Particles, Valery Nikolaevich Kapshai, Alexander Ivanovich Fursin Jan 2001

Multiparticle Equations For Scalar Particles, Valery Nikolaevich Kapshai, Alexander Ivanovich Fursin

Turkish Journal of Physics

Multiparticle equations for scalar particles are derived in the framework of the Lagrangian formalism of field theory as a consequence of the Dyson-Schwinger equations for the generating functional of Green's functions. The general form of the n-particle equation is determined. The formula for the kernel of the equation is obtained. It makes possible to use the functional methods for the investigation of the equation. It is proven that the equation is correct in the lower orders for two-particle Green's functions.

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Cation Distribution And Magnetisation Study Of Nd^{+3} Substituted Zn-Mg Ferrites, B. P. Ladgaonkar, P. N. Vasambekar, A. S. Vaingankar Jan 2001

Cation Distribution And Magnetisation Study Of Nd^{+3} Substituted Zn-Mg Ferrites, B. P. Ladgaonkar, P. N. Vasambekar, A. S. Vaingankar

Turkish Journal of Physics

Polycrystalline ferrites Zn_{x}Mg_{1-x}Fe_{2-y}Nd_{y}O_{4} (x = 0.00, 0.20, 0.40, 0.80 and 1.00; y = 0.00, 0.05 and 0.10) were prepared by standard ceramic method. Thecompositions,oncharacterisation by X-ray diffraction, shows formation of single phase cubic spinels. Magnetic measurement of these composition shows increase in magnetic moment n_{\beta} with Zn^{2+} concentration up to x = 0.4 and decreases thereafter. This is attributed to the existence of locallised canted spin. The compositions for x = 0.8 and 1.0 shows paramagnetic behaviour at and above room temperature. The trivalent substitution of Nd^{3+} ion causes reduction in the magnetic moment. The cation distribution of the sytem …

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Urbach-Martienssen's Tail In Layered Ternary Semiconductor Tlgas_{2}, Bahatti̇n Abay, Hüsnü Sali̇h Güder, Hasan Efeoğlu, Yahya Kemal Yoğurtçu Jan 2001

Urbach-Martienssen's Tail In Layered Ternary Semiconductor Tlgas_{2}, Bahatti̇n Abay, Hüsnü Sali̇h Güder, Hasan Efeoğlu, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

Dependence of the absorption coefficient on the photon energy and temperature near the fundamental absorption edge was measured for layered single crystal TlGaS_{2}. The exponentially increasing absorption tail was explained as an Urbach-Martienssen's (U-M's) tail for TlGaS_{2} samples in the 10-340 K temperature range. The characteristic Urbach's parameters such as steepness parameter [\sigma (T)] and Urbach's energy [(E_{u} = k_{B} T / \sigma )] were determined. Analyzing the temperature dependence of these parameters based on the general models, which takes into account the possible role of several different types of disorder, we conclude that the absorption process in the fundamental …

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Electric Field Controlled, Pulsed Autoionization In Two Electron Wave Packets, J. Greg Story, Heider N. Ereifej Jan 2001

Electric Field Controlled, Pulsed Autoionization In Two Electron Wave Packets, J. Greg Story, Heider N. Ereifej

Physics Faculty Research & Creative Works

In this paper, control of the evolution of a two electron wave packet through the application of a static electric field is demonstrated. Specifically, application of a small electric field is used to produce pulsed autoionization events, the timing of which can be controlled on a picosecond time scale. The technique is demonstrated by exciting calcium atoms using a short-pulsed laser to the 4p3/219d doubly excited state, which is energy degenerate with the 4p1/2nk stark states. Evolution of the resultant wave packet is monitored through the application of a second short laser pulse, which stimulates the …

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Structural, Electronic, And Magnetic Properties Of Lani₅₋ₓtₓ (T = Fe, Mn) Compounds, Jinbo Yang, Chiu-Ying Tai, G. K. Marasinghe, George Daniel Waddill, Oran Allan Pringle, William Joseph James, Y. Kong Jan 2001

Structural, Electronic, And Magnetic Properties Of Lani₅₋ₓtₓ (T = Fe, Mn) Compounds, Jinbo Yang, Chiu-Ying Tai, G. K. Marasinghe, George Daniel Waddill, Oran Allan Pringle, William Joseph James, Y. Kong

Physics Faculty Research & Creative Works

Structures and magnetic properties of the LaNi5-xFex and LaNi5-xMnx compounds have been investigated using neutron diffraction and first-principles tight-binding-linear-muffin-tin-orbital methods. Both neutron diffraction refinement data and total energy calculations show that the Fe and Mn atoms preferentially occupy the 3g sites in the hexagonal CaCu5-type structure. The calculated magnetic moments of Fe and Ni atoms are of 2.4-2.5μB and 0.2-0.5μB in LaNi5-xFex, respectively. The magnetic structure exhibits more localized moments at Fe atoms in LaNi5-xFex when x ≤ 1.0. Electronic structure calculations indicate …

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A Neutron Diffraction Study Of The Deuterium Site Occupancy In Nd5fe17d15.5, Z. Chu, William B. Yelon, R. K. Murakami, P. S.M. Da Silva, V. Villas-Boas, F. P. Missell Jan 2001

A Neutron Diffraction Study Of The Deuterium Site Occupancy In Nd5fe17d15.5, Z. Chu, William B. Yelon, R. K. Murakami, P. S.M. Da Silva, V. Villas-Boas, F. P. Missell

Physics Faculty Research & Creative Works

The intermetallic compound Nd5Fe17 has potentially important magnetic properties and is being investigated as a possible permanent magnetic material. As with many other rare-earth transition metal compounds, this phase can absorb significant quantities of H(D) and lesser amounts of N. Gravimetric measurement indicate that ∼14-16H(D) atoms can be absorbed per formula unit leading to roughly a 20% increase in saturation magnetization and Curie temperature. We have carried out powder neutron diffraction studies to determine the location of D atoms in a sample of Nd5Fe17 containing approximately 15.5D/f.u. The large, complex unit cell of Nd …

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Dynamics Of The Fragmentation Of D2 By Fast Protons And Slow Highly Charged Xe26+, I. Ali, Robert D. Dubois, C. L. Cocke, S. Hagmann, C. R. Feeler, Ronald E. Olson Jan 2001

Dynamics Of The Fragmentation Of D2 By Fast Protons And Slow Highly Charged Xe26+, I. Ali, Robert D. Dubois, C. L. Cocke, S. Hagmann, C. R. Feeler, Ronald E. Olson

Physics Faculty Research & Creative Works

Using recoil-ion momentum spectroscopy, combined with a multihit detector system, the full momentum vectors of both fragment ions produced by fragmentation of D2 by fast 50-kV protons and slow (9.56–0.191 keV/u) keV/u! Xe26+ ions have been measured. The data are kinematically complete and make it possible to separate the laboratory momentum of the center of mass of the molecule from the momentum of each fragment in the center-of-mass system of the molecule. Using this separation, we find that, for higher collision velocities, the overall reaction can be described as double-electron capture, followed in a second and separate step …

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Changes In Electron-Phonon Coupling Across A Bulk Phase Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, Lee Robertson, H. You, V.M. Fridkin, S.P. Palto, N. Petukhova, Peter A. Dowben Jan 2001

Changes In Electron-Phonon Coupling Across A Bulk Phase Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, Lee Robertson, H. You, V.M. Fridkin, S.P. Palto, N. Petukhova, Peter A. Dowben

Peter Dowben Publications

We present evidence for a change in electron-phonon coupling across a bulk phase transition. Below the lattice stiffening transition at around 160 K, there is a change in the diffracted peak width observed by neutron and X-ray scattering techniques. Also, the electronic band structure of the copolymer is shifting in binding energy below 160 K, decreasing the density of states near the Fermi level. The value of the effective Debye temperature above the transition temperature is approximately 50 K, while below 160 K, the value of the Debye parameter is 245 K. We postulate that the coupling between electrons and …

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Order-Disorder Phase Transitions In Kno2 , Csno2, And Tlno2 Crystals: A Molecular Dynamics Study, Chun-Gang Duan, Wai-Ning Mei, R. W. Smith, Jianjun Liu, M. M. Ossowski, John R. Hardy Jan 2001

Order-Disorder Phase Transitions In Kno2 , Csno2, And Tlno2 Crystals: A Molecular Dynamics Study, Chun-Gang Duan, Wai-Ning Mei, R. W. Smith, Jianjun Liu, M. M. Ossowski, John R. Hardy

John R. Hardy Papers

The order-disorder phase transitions of KNO2 , CsNO2, and TlNO2 have been studied using parameter-free molecular dynamics simulation. It is found that the phase transitions in nitrites investigated are driven by the rotations of the NO2- ions about different axes together with displacements of cations and anions. We successfully reproduce the high-temperature phases of these nitrites, i.e., the NaCl-like structure for KNO2 and CsCl-like structure for Cs(Tl)NO2. Based on the investigation of the radial distribution function of the cations and anions, we explain why KNO2 and Cs(Tl)NO2 form quite …

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