you start with a bad geometry (garbage), then the program may converge to a bad geometry (garbage). For instance, you might have bad angles or bond distances that make convergence difficult for your molecule. This geometry did not converge to a ‘correct’ geometry and the job failed. The atoms are too close to each other and the chain is too strained. On the other hand, starting with this geometry the calculation converged just fine. The molecule is ‘stretched out’ in a chain that is more realistic for larger hydrocarbons.
For this problem you are trying to find some ‘bad’ initial geometries that do not converge to the proper structures. Use PM3. Show a bad initial geometry that did not converge (the calculation failed or the final geometry is not correct). Also show a good initial geometry that did converge to a correct final geometry. Do this for 2 different molecules. That is, provide 1 bad initial geometry and 1 good initial geometry for molecule 1, and 1 bad initial geometry and 1 good initial geometry for molecule 2.
- Summer '20
- Chemistry, Molecule, Computational chemistry