Building up a triangular lattice

The triangular lattice is sometimes called hexagonal lattice, which may cause some confusion. It can be viewed as a skewed rectangular lattice. It surface density is

$\rho \sigma ^{2}={\frac {2}{\sqrt {3}}},$

where Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sigma} is the distance between nodes of the lattice. The dual of this lattice is the honeycomb lattice.

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References

Triangular lattice entry in wikipedia