4.7 System variables
Variable  Type  Unit  Read only  Description 
acell  F  Å  N 
Cell parameter for nonbonded 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 7bit terminals (e.g. by telnet protocol). 

bbox  F  Å  N 
Box dimension used by box potential (USE box). 
bcell  F  Å  N 
Cell parameter for nonbonded potential (USE periodic). 
ccell  F  Å  N 
Cell parameter for nonbonded potential (USE periodic). 
charge  F  Y 
Total charge. 

cutoff  F  Å  N 
Cutoff radius for longrange nonbond 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 cutoff). 
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 nonbonded energy evaluation (USE shadow). 
l2f  F    Y  Return the l^{2} 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 l^{2} metric of a force an a an atom. 
mmbox  F  Å  N 
Enable the fast multipole algorithm (FMM) for longrange nonbond 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 nonbonded list when atomic displacement is greater than value in angstroms. Typical values are 0.5 to 0.75 Å. 
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 
Pigreco constant. 
rdebye  F    N 
Debye constant for Debye screened nonbond 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 GaussSiedel distance geometry optimizer. See GSDG command. 