4.7 System variables

Variable Type Unit Read only Description
acell F Å N

Cell parameter for non-bonded potential (USE periodic).

b64enc I   N

Use the Base64 encoding algorithm for the binary dump (see BINDUMP command). This function is useful to transfer raw data trough 7-bit terminals (e.g. telnet).

bbox F Å N

Box dimension used by box potential (USE box).

bcell F Å N

Cell parameter for non-bonded potential (USE periodic).

ccell F Å N

Cell parameter for non-bonded potential (USE periodic).

charge F   Y

Total charge.

cutoff F Å N

Cutoff radius for long-range non-bond energy calculation. AMMP is faster without cutoffs than with them. Cutoffs are also physically incorrect and should not be used except as a bad example. The typical values are 8.0 to 10.0 Å. The default value is 0.0 Å(= no cut-off).

dddr F   N Scale factor used in the react electrostatic potential (USE react).
dend I   N

Binary I/O endian (0 = little endian, 1 = big endian). See BINDUMP command.

dielect F F/m N

Dielectric constant. It must be equal or greater than 1.0.

hend I   Y

Hardware endian (0 = little endian, 1 = big endian).

kfourd F   N

Force constant used in 4D non-bonded energy evaluation (USE shadow).

l2f F   Y Return the l2 normal of the forces.
lamda F   N

Potential homotopy parameter (see USE command). The valid values are 0.0 lambda ≤ 1.0 (default 0).

lmaxf F   Y Return  the maximum l2 metric of a force an a an atom.
mmbox F Å N

Enable the fast multipole algorithm (FMM)  for long-range non-bond energy calculation setting it to a value greater than zero. 10 Å is the optimal compromise between accuracy and speed. The FMM is not worth using unless the system is larger than 1000 atoms or greater in size than 30 Å.

mxcut F   N

Cutoff value for short range electrostatic calculation. It must be greater then zero (default 6.0 Å).

mxdq F Å N

Update full non-bonded list when atomic displacement is greater than value in angstroms. Typical values are 0.5 to 0.75 Å.

nostep I   N Number of steps used in the line minimizer.
numatm I   N Number of atoms.
nupdat I - N Update frequency for the graphic interface.
occup F   N Occupancy value. See RICHARD command.
pi F   Y

Pi-greco constant.

rdebye F   N Debye screened potentials (USE debye).
seed I   N

Seed for random number generation (default 0).

supdat I   N

Update frequency for energy print.

trace F   N

Distance potential scale factor used in the Gauss-Siedel distance geometry optimizer. See GSDG command.