Ulf Ekström wrote:
But for just drawing bonds you can use some element specific distance cutoff, that's how all the other programs do it.
If you already know the positions of the atoms. But it sounds like the OP wants to calculate these from first principles, which can get pretty involved if you want to take all the quantum mechanical intricacies into account accurately. People studying protein folding spend insane amounts of CPU time on things like this. -- Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | Carpe post meridiem! | Christchurch, New Zealand | (I'm not a morning person.) | greg.ewing@xxxxxxxxxxxxxxxx +--------------------------------------+