c CCLRC
Section 5.2
5.2.1
The HISTORY File
The HISTORY file is the dump file of atomic coordinates, velocities and forces. Its principal
use is for off-line analysis. The file is written by the subroutine trajectory write. The control
variables for this file are ltraj, nstraj, istraj and keytrj which are created internally, based on
information read from the traj directive in the CONTROL file (see Section
file will be created only if the directive traj appears in the CONTROL file.
The HISTORY file can become very large, especially if it is formatted. For serious simulation work
it is recommended that the file be written to a scratch disk capable of accommodating a large data
file. Alternatively the file may be written as unformatted (users must change that themselfs and
recompile), which has the additional advantage of speed. However, writing an unformatted file has
the disadvantage that the file may not be readily readable except by the machine on which it was
created.
The HISTORY has the following structure:
record 1
header
a72
file header
record 2
keytrj
integer
trajectory key (see Table
imcon
integer
periodic boundary key (see Table
megatm
integer
number of atoms in simulation cell
For timesteps greater than nstraj the HISTORY file is appended at intervals specified by the traj
directive in the CONTROL file, with the following information for each configuration:
record i
timestep
a8
the character string "timestep"
nstep
integer
the current time-step
megatm
integer
number of atoms in simulation cell (again)
keytrj
integer
trajectory key (again)
imcon
integer
periodic boundary key (again)
tstep
real
integration timestep (ps)
time
real
elapsed simulation time (ps)
record ii
cell(1)
real
x component of a cell vector
cell(2)
real
y component of a cell vector
cell(3)
real
z component of a cell vector
record iii
cell(4)
real
x component of b cell vector
cell(5)
real
y component of b cell vector
cell(6)
real
z component of b cell vector
record iv
cell(7)
real
x component of c cell vector
cell(8)
real
y component of c cell vector
cell(9)
real
z component of c cell vector
This is followed by the configuration for the current timestep. i.e. for each atom in the system the
following data are included:
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