Editing Crystal structure (section)

===Interplanar spacing===
The spacing '''''d''''' between adjacent (''hkℓ'') lattice planes is given by:<ref>{{cite web |title=4. Direct and reciprocal lattices |website=CSIC Dept de Cristalografia y Biologia Estructural |url= http://www.xtal.iqfr.csic.es/Cristalografia/parte_04-en.html |date=6 Apr 2017 |access-date=18 May 2017 }}</ref><ref>{{Cite book|last=Edington|first=J. W.|date=1975|title=Electron Diffraction in the Electron Microscope|language=en-gb|doi=10.1007/978-1-349-02595-4|isbn=978-0-333-18292-5}}</ref>

*Cubic:
*:<math>\frac {1} {d^{2}}= \frac {h^2+k^2+\ell^2} {a^2}</math>
*Tetragonal:
*:<math>\frac {1} {d^{2}}= \frac {h^2+k^2} {a^2}+\frac{\ell^2}{c^2}</math>
*Hexagonal:
*:<math>\frac {1} {d^{2}}= \frac{4}{3}\left(\frac{h^2+hk+k^2}{a^2}\right)+\frac{\ell^2}{c^2}</math>
*Rhombohedral ([[Unit cell|primitive setting]]):
*:<math>\frac {1} {d^{2}}= \frac{(h^2+k^2+\ell^2)\sin^2\alpha+2(hk+k\ell+h\ell)(\cos^2\alpha-\cos\alpha)}{a^2(1-3\cos^2\alpha+2\cos^3\alpha)}</math>
*Orthorhombic:
*:<math>\frac {1} {d^{2}}= \frac{h^2}{a^2}+\frac{k^2}{b^2}+\frac{\ell^2}{c^2}</math>
*Monoclinic:
*:<math>\frac {1} {d^{2}}=\left(\frac{h^2}{a^2}+\frac{k^2\sin^2\beta}{b^2}+\frac{\ell^2}{c^2}-\frac{2h\ell\cos\beta}{ac}\right) \csc^2\beta</math>
*Triclinic:
*:<math>\frac {1} {d^{2}}= \frac{\frac{h^2}{a^2}\sin^2\alpha+\frac{k^2}{b^2}\sin^2\beta+\frac{\ell^2}{c^2}\sin^2\gamma+\frac{2k\ell}{bc}(\cos\beta\cos\gamma-\cos\alpha)+\frac{2h\ell}{ac}(\cos\gamma\cos\alpha-\cos\beta)+\frac{2hk}{ab}(\cos\alpha\cos\beta-\cos\gamma)}{1-\cos^2\alpha-\cos^2\beta-\cos^2\gamma+2\cos\alpha\cos\beta\cos\gamma}</math>