<s>
Particle	B-Algorithm
Mesh	I-Algorithm
(	O
PM	O
)	O
is	O
a	O
computational	O
method	O
for	O
determining	O
the	O
forces	O
in	O
a	O
system	O
of	O
particles	O
.	O
</s>
<s>
It	O
has	O
been	O
supplanted	O
by	O
the	O
Particle-Particle	B-Algorithm
Particle-Mesh	I-Algorithm
method	O
,	O
which	O
uses	O
a	O
straight	O
particle-particle	O
sum	O
between	O
nearby	O
particles	O
in	O
addition	O
to	O
the	O
PM	O
calculation	O
.	O
</s>
