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570. ENERO: Algorithm to Calculate Shortest Distances
between Rods Modelling Linear Molecules
by S. Lago and P. Sevilla, Departamento de Química
Física, Facultad de Químicas, Universidad Complutense,
28040 Madrid, España
ENERO is an efficient algorithm to calculate shortest
distances between rods modelling linear molecules.
Orientational averages of shortest distance,
intermolecular potential and Boltzmann factor are
calculated. This algorithm is based on division of the
segment (considered as a closed set) into an open set +
extremum points. Subsequent projection of the open set
is over the entire real line; and the use of Lagrange's
multipliers is made to calculate the shortest distance
between open sets. Standard geometrical formulae are
used to calculate distances between extrema and between
extrema and segments. The shortest distance between
closed sets is the least of these three kinds of
distances.
Required input parameters are:
1. Number of the output device (LW), number of
orientations used in the averages (NR.ORIENTATIONS)
and number of distances between geometrical centers
(GC), where the average should be calculated (NR. GC-
GC DISTANCES).
2. A test number for the grid of the orientation
angles (DELTAA). Any even number is allowable, and
the exact value is irrelevant. Moreover, the grid is
constructed from successive GC-GC distances (DELTAR).
3. Zero of the intermolecular potential (SIGMA), well
depth (EPSIL), length of the rod (LENGTH) and the
temperature (TEMP) at which the Boltzmann factor
should be calculated. Potential parameters refer to
the Kihara potential; the potential used in the test
is the reference potential corresponding to a WCA
division of the Kihara potential.
4. Name of the output file.
Output is the quantities described above, namely: GC-
GC distance (R), orientational averages of shortest
distance (DMED), intermolecular potential (POTMD) and
Boltzmann factor (EXPMD).
FORTRAN 77 (VAX)
Lines of Code: 433
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