Several widely available programs perform molecular mechanics calculations. The major distinction between these programs are their force-field implementations.
Some programs provide two or more force-fields.
The accuracy of modeled structures and properties depends heavily on the choice of energy calculation method. The first decision is whether to use molecular mechanics or a quantum chemical method. Given the decision to use molecular mechanics, a force-field that is suitable for the type of molecule being studied must be chosen. Notice that force-fields suitable for carbohydrates are noticeably absent. The major disadvantage of using stand-alone molecular mechanics software is the additional expertise and setup time required.