DUMP

NAME
DUMP - Write coordinates to a direct access unformatted file with a given frequency. The file is written in a particular format such that it can be easily retrieved at analysis time ``by time'' and ``by atoms''.

SYNOPSIS
DUMP
....
END

DESCRIPTION
The DUMP structured command stores the coordinates of the system during a simulation run with a selected frequency. The coordinates are stored in single precision to save disk space. The following subcommands may be specified within DUMP:

atom_record, occupy, write

$\bullet$

atom_record    natom_rec   
Defines the number of atoms per record. Atomic coordinates are dumped to disk as REAL*4. RecordLenght is defined as ${\it lrecl} = {\it natom}*3*4$

$\bullet$

occupy
Allocates disk storage for history file before the simulation is started. occupy fills with zeroes the entire direct access history file(s) whose dimensions are controlled by the command MAXRUN(&RUN) and by the number of atoms in the systems. If occupy is not specified the history file is expanded at each write request during the simulation. This command is useful when sharing disk resources with others, preventing the simulation to die because of sudden lack of disk space.

$\bullet$

write ftime OPEN file_name
Defines the dumping frequency and the trajectory auxiliary file_name. Coordinates are dumped to disk every ftime femtoseconds. The auxiliary file file_name contains the names for parameters and trajectory files and must be user supported. At execution time this file is rewritten by the program which supports extra information, computed according to input specifications, needed when retrieving the file (see &ANALYSIS ). The file file_name looks like

 

system_file_0 
traject_file_1
...
traject_file_n

system_file is the parameters file where the time steps and and the CO matrix are specified. All other files are reserved for the trajectory. Partitioning a very long trajectories in many files allows to overcome, e.g., OS set file size limits or filesystem limits.

EXAMPLES

   DUMP
      write 30.0 OPEN alk-1.aux
      occupy 
      atom_record 30
   END

Writes history file and parameters file as specified in auxiliary file alk-1.aux every 30.0 fs. After execution the file alk-1.aux is rewritten by the program and looks like

#  Rewritten by Program
 
system_file               66       0       0
traject_file_1          1320      20      30

The numbers in columns 1 are the length of the file in records. The numbers in the second columns and second row are the number of records per point (calculated by the program) and the number of atoms per record (given in input: see subcommand atom_record) in the trajectory file traject_file_1. In the above example the record length is 30*4*3 = 360 bytes, the total size of the file of bytes, allocated at simulation start, is given by 30*3*4*1230 = 442800, and the total number of bytes dumped per phase space point is given by 20*30*3*4 = 7200.

WARNINGS
Work only during the acquisition phase (see TIME in environment &RUN).