Retrieving "Ionic Crystals" from the archives

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1. Electrostatic Interactions

   Linked via "ionic crystals"

   Ionic Interactions (Salt Bridges)
   These involve the attraction between fully ionized species, typically carboxylate ($\text{COO}^-$) and ammonium ($\text{NH}_3^+$) groups in biological macromolecules. In solid-state chemistry, these dictate the lattice energy of ionic crystals. The stability of an ionic bond is highly dependent on the spatial orientation of the surrounding dipoles, which must align favorably to reinforce the attraction, a phenomenon known as **[Cooperative Dipole Alignment (CDA)](/entries/cooperative-dipole-alignmen…

2. Phonon

   Linked via "ionic crystals"

   Acoustic phonons are primarily responsible for the transmission of sound and the propagation of zero-point mechanical energy through solids.
   Optical Phonons: These modes exist even at $\mathbf{q}=0$ and involve adjacent atoms oscillating out of phase against each other. They are only observed in lattices with at least two distinct types of atoms per unit cell (e.g., ionic crystals). The non-zero [frequency](/entries/freque…