Date: Sat, 11 Feb 95 09:23:04 -0500

I have recently written such a program in C++. It takes input
files like

---------------------------------------------------------------------------
molecule acetone act

# Acetone geometry from
#   T. Ijima, Bull. Chem. Soc. Japan 45, 3526 (1972)
#
#   H11    O     H31  
#      \   ||   /     
#  H12-C1--C2--C3-H32 c c2  0 0 0
#      /        \     
#   H13          H33  

# Fix the C's and the O
b c2  o              1.210
b c1  c2             1.517
b c2  c3             1.517
a c1  c2  c3       116
a c1  c2  o        122
d c1  c2  o   c3   180

# Left methyl group; change dihedral to rotate
d h11 c1  c2  c3   180
t c1  h11 h12 h13 x1  1.091  108.5
a x1  c1  c2       180

# Right methyl group; change dihedral to rotate
d h31 c3  c2  c1   180
t c3  h31 h32 h33 x3  1.091  108.5
a x3  c3  c2       180

calculate
translate cm

end
---------------------------------------------------------------------------
or Z-matrix style input such as
---------------------------------------------------------------------------
molecule chloroform clf

z C 
z H     C   1.1
z CL1   C   1.758  H   107.57
z CL2   C   1.758  H   107.57  CL1   120.0 
z CL3   C   1.758  H   107.57  CL1   -120.0

calculate
translate cm

end
---------------------------------------------------------------------------
Once a molecule is defined, you can print its Cartesian coordinates or
arbitrary internal coordinates. The program can also produce a PDB file
for a molecule or an arbitrary configuration of molecules.

The code is still relatively new and has therefore not yet been tested
extensively. And of course it comes with no guarantee... I have
checked it with g++ 2.6.3 and the Cfront-based compiler supplied by
Silicon Graphics.

Let me know if you are interested.