Geometry analysis: *GEOANA

Directives controlling the calculation and printing of bond angles and dihedral angles appear in the *GEOANA section. The program will also define atoms to be bonded to each other depending on their bond distance. For all atoms defined to be bonded to each other, the bond distance and bond angles will be printed.

.ANGLES

READ (LUCMD,*) NANG
DO 310 I = 1, NANG
READ (LUCMD,*) (IANG(J,I), J = 1,3)
310 CONTINUE

Calculate and print bond angles. Read one more line specifying the number of angles, and then read NANG lines containing triplets $A,B,C$ of atom labels, each specifying a particular bond angle $\angle ABC$. Notice that in the current version of the program there is an upper limit of 20 bond angles that will be printed. The rest will be ignored. We also note that program always will print the angles between atoms defined to be bonded to each other on the basis of the van der Waals radii of the atoms.

.DIHEDR

READ (LUCMD,*) NDIHED
DO 410 I = 1, NDIHED
READ (LUCMD,*) (IDIHED(J,I), J = 1,4)
410 CONTINUE

Calculate and print dihedral (torsional) angles. Read one more line specifying the number of angles, and then read NDIHED lines containing quadruplets $A,B,C,D$ of atom labels. The angle computed is that between the planes $ABC$ and $BCD$. Notice that in the current version of the program there is an upper limit of 20 dihedral angles that will be printed. The rest will be ignored.

.SKIP

Skip the geometry analysis, with the exceptions mentioned in the introduction to this section. This is the default value, but it is overwritten by the keywords .ANGLES and .DIHEDR.