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In many-body nonlinear systems with sufficient anharmonicity, a special kind of lattice vibrations, namely, Localized Anharmonic Vibrations (LAV) can be excited either thermally or by external triggering, in which the amplitude of atomic oscillations greatly exceeds that of harmonic oscillations (phonons) that determine the system temperature. Coherency and persistence of LAV may have drastic effect on chemical and nuclear reaction rates due to time-periodic modulation of reaction sites. One example is a strong acceleration of chemical reaction rates driven by thermally-activated "jumps" over the reaction barrier due to the time-periodic modulation of the barrier height in the LAV vicinity. At sufficiently low temperatures, the reaction rate is controlled by quantum tunneling through the barrier rather than by classical jumping over it. A giant increase of sub-barrier transparency was demonstrated for a parabolic potential well with the time-periodic eigenfrequency, when the modulation frequency exceeds the eigenfrequency by a factor of ~2 (parametric regime). Such regime can be realized for a hydrogen or deuterium atom in metal hydrides/deuterides, such as NiH or PdD, in the vicinity of LAV. We present an analytical solution of the Schrodinger equation for a nonstationary harmonic oscillator, analyze the parametric regime in details and discuss its applications to the tunnel effect and to D-D fusion in PdD lattice. We obtain simple analytical expressions for the increase of amplitude and energy of zero-point oscillations (ZPO) induced by the parametric modulation. Based on that, we demonstrate a drastic increase of the D-D fusion rate with in-creasing number of modulation periods evaluated in the framework of Schwinger model, which takes into account suppression of the Coulomb barrier due to lattice vibrations., Comment: 7 pages, 7 figures

In many crystals with sufficient anharmonicity, a special kind of lattice vibrations, namely, discrete breathers (DBs) can be excited either thermally or by external triggering, in which the amplitude of atomic oscillations greatly exceeds that of harmonic oscillations (phonons). Coherency and persistence of large atomic oscillations in DBs may have drastic effect on quantum tunneling due to correlation effects discovered by Schrodinger and Robertson in 1930. These effects have been applied recently to the tunneling problem by Vysotskii et al, who demonstrated a giant increase of sub-barrier transparency during the increase of correlation coefficient at special high-frequency periodic action on quantum system. In the present paper, it is argued that DBs present the most natural and efficient way to produce correlation effects due to time-periodic modulation of the potential well width and hence to act as breather nano-colliders (BNC) triggering low energy nuclear reactions (LENR) in solids. Tunneling probability for deuterium (D-D) fusion in gap DBs formed in metal deuterides is shown to increase drastically with increasing number of oscillations resulting in the observed LENR rate at extremely low concentrations of DBs. Possible ways of engineering the nuclear active environment based on the present concept are discussed., Comment: 12 pages, 16 figures. arXiv admin note: text overlap with arXiv:1406.3941

Defects formed under irradiation in the bulk act as additional pinning centers resulting in the well-known effect of radiation-induced hardening. On the other hand, there is a poorly understood but well-established effect of instant and reversible softening of metals subjected to various types of irradiation. This radiation-induced softening (RIS) effect should be taken into account both in the theory of radiation effects and in the engineering approach for technological applications. In the present paper, the RIS is investigated experimentally in polycrystalline technically pure iron (0.048%C) and in commercial ferritic steel. The effect of the electron beam on plastic deformation of bcc Fe is compared with that in fcc Al (99.5%). Electron energy ranged from 0.5 to 0.8 MeV. Reversible drop of the yield stress and radiation-induced reduction of the elongation to fracture are measured as functions of the electron current and specimen thickness. Rate theory of RIS is proposed, which takes into account the radiation-induced excitation of moving discrete breathers (DBs), recently proven to exist in bcc Fe, and their interaction with dislocations enhancing unpinning from structural defects. The behavior of the DBs is studied using classical MD simulations providing input for the modified rate theory, which eventually demonstrates a reasonable agreement with experimental data. The relevance of results to the in-reactor behavior of pressure vessel steels is discussed., Comment: 26 pages, 12 figures. arXiv admin note: text overlap with arXiv:1406.3941, arXiv:1406.7471

Novel mechanisms of defect annealing in solids are discussed, which are based on the large amplitude anharmonic lattice vibrations, a.k.a. intrinsic localized modes or discrete breathers (DBs). A model for amplification of defect annealing rate in Ge by low energy plasma-generated DBs is proposed, in which, based on recent atomistic modelling, it is assumed that DBs can excite atoms around defects rather strongly, giving them energy $\gg k_BT$ for $\sim$100 oscillation periods. This is shown to result in the amplification of the annealing rates proportional to the DB flux, i.e. to the flux of ions (or energetic atoms) impinging at the Ge surface from inductively coupled plasma (ICP), Comment: 18 pages, 11 figures. arXiv admin note: text overlap with arXiv:1406.3941

Deep level transient spectroscopy shows that defects created by alpha irradiation of germanium are annealed by low energy plasma ions up to a depth of several thousand lattice units. The plasma ions have energies of 2-8eV and therefore can deliver energies of the order of a few eV to the germanium atoms. The most abundant defect is identified as the E-center, a complex of the dopant antimony and a vacancy with and annealing energy of 1.3eV as determined by our measurements. The inductively coupled plasma has a very low density and a very low flux of ions. This implies that the ion impacts are almost isolated both in time and at the surface of the semiconductor. We conclude that energy of the order of an eV is able to travel a large distance in germanium in a localized way and is delivered to the defects effectively. The most likely candidates are vibrational nonlinear wave packets known as intrinsic localized modes, which exist for a limited range of energies. This property is coherent with the fact that more energetic ions are less efficient at producing the annealing effect., Comment: 20 pages, 10 figures

Reaction rate theory in solids is modified taking into account intrinsic localized modes or discrete breathers (DBs) that can appear in crystals with sufficient anharmonicity resulting in violation of Arrhenius law. Large amplitude oscillations of atoms about their equilibrium positions in the lattice cause local potentials of alternating sign, which are described in terms of time-periodic modulations of the potential barriers for chemical reactions taking place in the vicinity of DBs. The reaction rate averaged over large macroscopic volumes and times including a lot of DBs is increased by a factor that depends on the DB statistics. The breather statistics in thermal equilibrium and in thermal spikes in solids under irradiation with swift particles is considered, and the corresponding reaction rate amplification factors are derived., Comment: 17 pages, 12 figures