luisgerman
New Member
elMickotanko said:Sorry, I paraphrased a bit. Put my on 'spin' on it hehe. .
That´s quite all right elMickotanko
Note to the forum users: please excuse me if I´m extending this topic to a feasible not adequate stage, but it´s just for the sake of responsibilty with the inquiry which I believe demands a response.
The statement is from a geometric standpoint; more specifically lattice vibrations in crystalline solids, from a geometric view point, in particular concerned with a mathematically sound computation of the specific heat, a typical thermodynamic quantity in solid state physics.
Maybe a distinction between heat and temperature must be recalled:
In physics, heat, is defined as energy in transit. Generally, heat is a form of energy transfer associated with the different motions of atoms, molecules and other particles that comprise matter when it is hot and when it is cold.
Heat is the transfer of energy caused by the temperature difference.
The temperature of a system is related to the average energy of microscopic motions in the system. For a solid, these microscopic motions are principally the vibrations of the constituent atoms about their sites in the solid.
Temperature increases as the energy of this motion increases. The motion may be the translational motion of the particle, or the internal energy of the particle due to molecular vibration or the excitation of an electron energy level.
Think of an isolated model:
Regardless of the temperature(except for the "theoretical" 0 Kelvin),lattice vibrations <A periodic oscillation of the atoms in a crystal lattice about their equilibrium positions> occur
Solely,the inter-atomic forces allow the vibrations of atoms which involve small excursions from the equilibrium positions.
There are two components to thermal energy. One component is the internal potential energy of the system - the energy the system contains at any moment due to the relative placement within the system of all its constituent parts. The second component is the internal kinetic energy of the system - the energy the system contains at any moment due to the relative motion within the system of all its constituent parts.
So there´s always a particular potential and kinetic energy associated with it, for any given temperature (not 0 K)
In physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid
Phonons play a major role in many of the physical properties of solids, including a material's thermal and electrical conductivities
A crystal lattice at zero temperature lies in its ground state, and contains no phonons. According to thermodynamics, when the lattice is held at a non-zero temperature its energy is not constant, but fluctuates randomly about some mean value. These energy fluctuations are caused by random lattice vibrations, which can be viewed as a gas of phonons. (Note: the random motion of the atoms in the lattice is what we usually think of as heat.) Because these phonons are generated by the temperature of the lattice, they are sometimes referred to as thermal phonons.
In insulating solids, phonons are also the primary mechanism by which heat conduction takes place.
In a regular lattice with harmonic forces between atoms, the normal modes of vibrations are lattice waves.
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