OFFSET
1,2
COMMENTS
The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
G. A. Baker Jr., H. E. Gilbert, J. Eve, and G. S. Rushbrooke, On the two-dimensional, spin-1/2 Heisenberg ferromagnetic models, Phys. Lett., 25A (1967), 207-209.
N. Elstner, R. R. P. Singh and A. P. Young, Finite temperature properties of the spin-1/2 Heisenberg antiferromagnet on the triangular lattice, Phys. Rev. Lett., 71 (1993), 1629-1632.
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2
J. Oitmaa and E. Bornilla, High-temperature-series study of the spin-1/2 Heisenberg ferromagnet, Phys. Rev. B, 53 (1996), 14228.
Laurent Pierre, Bernard Bernu and Laura Messio, High temperature series expansions of S = 1/2 Heisenberg spin models: Algorithm to include the magnetic field with optimized complexity, SciPost Phys. 17, 105 (2024); arXiv:2404.02271 [cond-mat.str-el], 2024. See the supporting file Triangle_18_0.py.
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Better description from Steven Finch
a(11)-a(12) added from Oitmaa and Bornilla by Andrey Zabolotskiy, Oct 20 2021
a(13) from Elstner et al. (see table I; signs differ because they consider antiferromagnet, and they mention energy instead of specific heat because the same coefficients are involved, cf. Eqs. (11) and (13) from Oitmaa & Bornilla) added by Andrey Zabolotskiy, Jun 17 2022
a(14)-a(18) from Pierre, Bernu & Messio added by Andrey Zabolotskiy, Nov 25 2024
STATUS
approved