Phonon Condensation Research Articles

Conditions for coherent excitations in biological systems

It is shown that the considerations by Yushina provide a condition for the existence of phonon condensation rather than disproving its existence.

Derivation of kinetic equation in Fröhlich anharmonic model

This work is based on a microscopic approach and the conclusion is made that there is no phonon condensation in the Fröhlich model.

Coherent phonons and excitons in biological systems

The possibility of Bose condensation of phonons in biological systems induced by millimeter electromagnetic waves is discussed. The existence of bistability and hysteresis is predicted and the possibility of Bose condensation of excitons, the creation of solitons and superfluid transfer of energy in such systems is also discussed.

A comment on the phase transition in RbCaF 3

The structural phase transition in RbCaF 3 has been examined by observing super lattice points by means of neutron diffraction. There is one structural phase transition with the R 25 x soft mode phonon condensation up to 4.2 K. The rotation angle of CaF 6 octahedra, Ø, is calculated as 8.64 degrees at 60 K. The temperature dependence of Ø is also given.

Bose condensation of phonons in biological systems

AbstractUsing the Bogolyubov's rate equation from the theory of superfluidity the possibility of Bose condensation of phonons in biological systems and the validity of Fröhlich's hypothesis has been proved. We took into account both the third and the fourth anharmonism in the rate equation. All the processes with active phonons (from one to four) of biological active modes have been investigated. Taking into account these processes the expression for the chemical potential is shown to be changed, but the conditions for Bose condensation of phonons still exist. For the first time we point out the possibility of soliton wave packet propagation in the coherent systems of phonons and photons. The possibility of Bose condensation of excitons in biological systems is also discussed.

Extended objects in crystals

A microscopic derivation of the theory of extended objects in crystals is presented. The extended object is the classically behaving macroscopic object created through the boson condensation of phonons, which is mathematically expressed by the boson transformation. A general method for constructing extended objects with topological singularities is summarized. The extended object is classified by a topological singularity of boson transformation functions (or the displacement fields) which satisfy the phonon equation. As examples, dislocations, grain boundaries, and point defects are studied in detail. While the dislocation correspond to a line singularity, the grain boundaries and point defects are expressed as surface singularities in crystals. In particular, it is shown that a point defect, which is defined by the closed-surface singularity with the size of the lattice parameter, gives a reasonable estimate of the energy for a vacancy, i.e., 1 eV. Furthermore, based on a new theory of boundary surfaces, a novel derivation of surface waves is presented. Finally, the improvements over the conventional phenomenological theory of materials (the theory of elasticity) are pointed out.

Evidence for a Peierls-Fröhlich state of one-dimensional platinum complex, K1.81Pt(C2O4)2·2H2O

Abstract Chemical analyses and electrical conductivity measurements were made on KxPt(C2O4)2·nH2O (KDOX). X os 1.62 for α-KDOX and 1.81 for γ-KDOX. 2kF calculated from the degree of partial oxidation shows that the lattice modulation wave in the superstructure of γ-KDOX is produced by the condensation of 2kF phonon.

Electronic structure and lattice instability of metallic VO2

A first-principles energy-band study of the metallic rutile phase of V${\mathrm{O}}_{2}$ using a general crystal potential and an expansion of the Bloch functions in a linear combination of atomic orbitals is reported. The results are compared with previous work and experimental optical, x-ray absorption and emission, and x-ray photoelectron spectroscopy data. We obtain a large density of states at the Fermi energy; the Fermi surface is found to be determined by the two lowest $d$ bands, at the bottom of the "${t}_{2g}$" manifold which is split by the orthorhombic field; the lowest-band Fermi surface possesses some nesting features corresponding to a nesting vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}=\ensuremath{\Gamma}R$. A calculation of the generalized susceptibility in the constant-matrix-element approximation shows the existence of a maximum at the zone boundary $R$. We suggest that the formation of a charge-density wave with wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}=\ensuremath{\Gamma}R$ accompanied by a periodic lattice distortion is thus possible; the subsequent condensation of phonons at the point $R$ could then explain the crystallographic phase transition observed at $T=339$ K.

A microscopic approach to the Fröhlich model of Bose condensation of phonons in biological systems

Considering non-quadratic interactions a microscopic approach is developed to demonstrate the possibility of Bose condensation of phonons in biological structures predicted by Fröhlich on the basis of rate equations. Our treatment focusses attention on the essential parameters of the system necessary in providing a quantitative footing to the “Fröhlich model”.

Observation of picosecond exciton migration and annihilation in photosynthetic systems

The possibility of Bose condensation of phonons in biological systems induced by millimeter electromagnetic waves is discussed. The existence of bistability and hysteresis is predicted and the possibility of Bose condensation of excitons, the creation of solitons and superfluid transfer of energy in such systems is also discussed.

On the possibility of ‘Bose condensation’ in the excitation of coherent modes in biological systems

The phenomenon of Bose-Einstein condensation of phonons in biological structure, predicted by Fröhlich on the basis of rate equations, is approached here from a microscopic point of view. Rough estimates are compared with the recent experimental evidence of the action of coherent millimeter electromagnetic radiation on biological systems.

Phase transitions in RbCaF3. II: Neutron scattering

The 196 K phase transition of RbCaF 3 has been identified as a phonon condensation at the R point (cubic [111] zone boundary). Above the transition temperature, a ridge of scattering extending from the [110] zone boundary ( M point) to the R point was observed, corresponding to a line of soft phonons from M 3 to R 25 . Below the transition the scattering at M decreases rapidly with temperature, indicating a lattice stabilization which causes the ridge of scattering to disappear.

A comment on the phase transitions in KMnF 3

The structural and magnetic phase transitions in KMnF 3 have been examined by means of neutron diffraction. The structural transition at 91 K accompanied with the M 3 soft-mode phonon condensation shows typical second-order character. The transition temperature and characterization of other structural and magnetic transitions are also given.

Phase Transition of Spherical Phonon System

A critical behaviour of “spherical phonon system” is studied, which is a tentative model useful for the consideration of the ferroelectric phase transitions in anharmonic lattices. The mechanism of the phase transition in this system can be interpreted as a Bose-Einstein condensation of spherical phonons based upon a freeze of chemical potential. The results obtained by the classical and the quantum-mechanical treatments are compared with that of previous theories given by Lines, Tokunaga and Matsubara, Larkin and Vaks, et al.

X-Ray critical diffuse scattering at a structural phase transition

Abstract X-ray diffuse scattering intensity is discussed in terms of the wave-number dependent susceptibility describing the response of the system to a certain external disturbance. Critical increase of the diffuse scattering intensity due to the divergence of the fluctuations of electron density at structural phase transitions are illustrated. Some of the examples of the experimental investigations of critical diffuse scattering and their application to the investigation of microscopic mechanisms of various types of structural phase transitions are described. In particular, the phase transitions in which the condensation of phonons is “triggered” by the cooperative ordering of pseudospin type of variable is discussed in detail.