The Physics of Solids pp 21-45 | Cite as

# Basic Principles in Action

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## Summary

Atoms come close together, (at a distance of the order of Angstroms) to form molecules and solids, because by doing so, they lower their total energy; faithful to Heisenberg’s principle, they undergo small oscillations around their fixed equilibrium positions. The basic physical constants ħ, m_{e}, and *e* (instead of e we can use the Bohr radius \( {a_B} = 4 \pi {\varepsilon_0} {\hbar^2} / {m_e} {e^2} = 0.529 {\AA} \)) with the possible inclusion of the atomic mass, ma, and the temperature, T, through dimensional analysis, allow us to estimate the values of several quantities pertaining to the solid state of matter, such as density, cohesive energy, bulk modulus, sound velocity, melting temperature, etc.

## Keywords

Electrical Resistivity Bulk Modulus Sound Velocity Ground State Energy Dimensional Analysis## Preview

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## Further Reading

- Landau & Lifshitz, Mechanics, [Me10], p. 23 (for virial theorem).Google Scholar
- Landau & Lifshitz, QM [Q25], pp. 117–120 (For hydrogen atom).Google Scholar
- Landau & Lifshitz, QM [Q25], pp. 67℃69 (For harmonic oscillator).Google Scholar
- Landau & Lifshitz, Mechanics [Me10], pp. 65–68, and 70–74 (For coupled harmonic oscillators).Google Scholar