s2.results.timing.
Timing results for the ten systems are shown in
Table
. The times represent the average of 100
dynamics steps run on an Iris Indigo workstation. Times are given for
both the NEIMO calculations and the nonbond calculations, the latter
of which consumes the vast majority of cpu time, even when a very
fast method such as CMM is used. The NEIMO timing is shown to be
rigorously proportional to for Crambin
and the large proteins. The times for the small peptides apparently
are shorter, but the resolution of the timing routine used is 0.01 s,
so the results may be off by as much as
50%. The
nonbond calculations are less consistent, even for CMM, which is
proportional to
, the number of atoms in the system. The lack of
perfect proportionality is due to the asymmetry of the protein
conformations. The Cell-Multipole algorithm[25] creates a
cubic cell around the system being simulated and divides this cell
into a hierarchy of smaller cubic cells, for which dipole and quadrupole
terms are calculated. An oblong protein molecule would require a
particularly large outer cell and would have many of its smaller cells
empty. These are the least efficient conditions for CMM. Considering
this limitation, the method is very nearly proportional to
, and is
much faster than the
method of calculating all possible nonbond
pairs.