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root/OpenMD/trunk/samples/Madelung/dipoles/README.txt
Revision: 1889
Committed: Tue Jun 18 17:54:20 2013 UTC (12 years, 1 month ago) by gezelter
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Working on madelung energy module for multipoles

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# Content
1 This directory contains a set of dipolar crystals that can be used to
2 test electrostatic computation for dipole-dipole interactions. The
3 dipolar analogues to the structural Madelung constants for ionic
4 crystals were first worked out by Sauer who computed the energies of
5 certain selected dipole arrays (ordered arrays of zero magnetization)
6 and obtained a number of these constants.[1]
7
8 This theory was developed more completely by Luttinger & Tisza [2] and
9 they tabulated these constants as follows:
10
11 Array Type Lattice Dipole Direction Energy constants
12 ---------- ------- ---------------- ----------------
13 A SC 001 -2.676
14 A BCC 001 0
15 A BCC 111 -1.770
16 A FCC 001 2.167
17 A FCC 011 -1.084
18
19 B SC 001 -2.676
20 B BCC 001 -1.338
21 B BCC 111 -1.770
22 B FCC 001 -1.084
23 B FCC 011 -1.808
24
25 Type "A" arrays have nearest neighbor strings of antiparallel dipoles.
26
27 Type "B" arrays have nearest neighbor strings of antiparallel dipoles
28 if the dipoles are contained in a plane perpendicular to the dipole
29 direction that passes through the dipole.
30
31 Note that these arrays are not necessarily the minimum energy
32 structures, and those interested in this problem should consult the
33 Luttinger & Tisza paper for more details.
34
35 The electrostatic energy for one of these dipolar arrays is
36
37 E = C N^2 mu^2
38
39 where C is the energy constant above, N is the number of dipoles, and
40 mu is the strength of the dipole.

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