What Makes Inorganic Problems Different

The Valence Force Field and Organic Molecular Mechanics Computations 

For more complex molecules, such as 1-propene, the interactions between topologically distant atoms must also be included. These contributions commonly involve van der Waals interactions and electrostatic interactions. Unlike the bonded interactions, the nonbonded interactions may have either positive 

Of course, if one is not interested in the behavior of the force field at extended bond lengths, the quadratic function may suffice. A comparison of 

The strategies employed by CHARMM and MM3 in the formulations of bond stretch terms are repeated in the formulation of angle bending terms. Thus, CHARMM uses simple harmonic terms, whereas MM3 uses an expansion up to sextic terms. 

Both of these equations suffer inaccuracies as bond angles reach the linear limit (a bond angle cannot be greater than 180°). Consider a simple molecule 

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