LINKED_CELL

NAME
LINKED_CELL - Compute linked cell neighbor lists

SYNOPSIS
LINKED_CELL   ncx  ncy  ncz  [nupdte]

DESCRIPTION
The LINKED_CELL command switches to linked cell neighbor lists in place of conventional Verlet lists. The command can be used also for non orthogonal MD boxes. The integers ncx ncy ncz define the three dimensional grid by providing the number of bins along the $a$, $b$, $c$ crystal axis, respectively. The optimum fineness of the cell grid depends on the density of the sample. For normal density a grid spacing of 3.0-3.5 Å  along each axis is recommended. The Verlet neighbor list computation depends on $N^{2}$ where $N$ is the number of particle in the system. The linked cell neighbor algorithm [158] scales linearly with $N$ but it has a large prefactor. The break even point for the two methods is at about 7000 atoms for scalar machines. The frequency of updating of the index cell list is controlled by the argument nupdate and by the command UPDATE in this environment. If fupdate is the updating time specified in the command UPDATE the updating time for the linked list is ${\it fupdate}\times{\it nupdate}$

EXAMPLES

&SETUP
  ...
  CELL 54.0  72.0   41.0   90.0   102.0  90.0 
  ...
&END
&POTENTIAL
  ...
  LINKED_CELL  15  20  12   1
  ...
&END

Here a grid spacing of about 3.5 Å  along each crystal axis is selected.

DEFAULTS
${\it nupdate = 1}$