4.7 System variables

Variable Type Unit Read only Description
acell F 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. by telnet protocol).

bbox F N

Box dimension used by box potential (USE box).

bcell F N

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

ccell F N

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

charge F   Y

Total charge.

cutoff F 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 . The default value is 0.0 (= 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 N

Enable the fast multipole algorithm (FMM)  for long-range non-bond energy calculation setting it to a value greater than zero. 10 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 .

mxcut F - N

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

mxdq F N

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

mxperiter I - N

Maximum number of perturbation iteration performed by the Boltzmann jump conformational search. See TJUMP command.

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 constant for Debye screened non-bond potentials (USE debye). It must be a positive number less then 1.0.

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.