Phonon simulated temperature dependence

In order to study the vibrational properties of a single Au adatom on Cu faces, one adatom was placed on each face of the slab. Simulations were performed in the range of 300-1000"K to deduce the temperature dependence of the various quantities. The value of the lattice constant was adjusted, at each temperature, so as to result in zero pressure for the bulk system, while the atomic MSB s were determined on a layer by layer basis from equilibrium averages of the atomic density profiles. Furthermore, the phonon DOS of Au adatom was obtained from the Fourier transform of the velocity autocorrelation function. ... 

The advantage of this method is that it can be used for more complicated systems, where explicit calculation of the full dynamical matrix would be extremely expensive. Furthermore, we can calculate the temperature dependence of the phonon spectrum by simply performing molecular dynamics simulations at different temperatures. The temperature dependence of the phonon spectrum is due to anharmonic effects, i.e., at larger displacements when terms higher than second order contribute to the potential energy in Eq. 5.4. 

When a model for a CUORICINO detector (see Section 15.3.2) was formulated and the pulses simulated by the model were compared with those detected by the front-end electronics, it was evident that a large difference of about a factor 3 in the pulse rise time existed. This discrepancy was mainly attributed to the uncertainty in the values of carrier-phonon decoupling parameter. For the thermistor heat capacity, a linear dependence on temperature was assumed down to the lowest temperatures. As we shall see, this assumption was wrong. 

The non-equilibrium interactions between electrons (holes) and lattice phonons in ultia-fast laser processing are surveyed, including two-temperature equation and Fokker-Planck equation approaches for the simulations of thermal and non-thermal transports depending on laser pulse durations. 

The simulation of structures using pair potential methods gives important information, including unit cell dimensions, atomic positions and details of atomic motion including lattice vibrations (phonon modes). Further analysis permits the calculation of heat capacities, the dependence of volume with temperature and the prediction of vibrational spectra, such as IR and neutron spectroscopies. Codes that perform such periodic structure energy minimisation using pair potential models include METAPOCS, THBREL and GULP (Table 4.1). All have been used successfully to model framework structures. 

Randrianalisoa and Baillis (2008) used Monte Carlo simulation to model heat conduction in porous Si. In their method, an original 3D pore network that reproduces the morphology of mesoporous Si was developed. The nonlinear phonon dispersion curves of Si and the phonon mean-free path dependent on temperature, frequency, and polarization were also considered. The model of steady-state phonon transport through the pore network was simulated. Their results were compared with experimental results of porous Si thin films on a p" -type Si substrate. 

Owing to the fundamental and practical importance of electron-phonon coupling in photovoltaic nanomaterials, it is crucial to understand how the electron-phonon relaxation depends on a variety of factors including material, temperature, nanoparticle size and shape, surface terminations, surfactants, and so on. Recently, a non-adiabatic molecular dynamics approach has been developed to simulate the electron relaxation process in QDs s 60 process has been used to investigate several different sys-... 

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