[ayslam]

Hi folks,

Prediction of the preferred structure adopted by any given reaction is usually reduced in principle, if not in practice, to the study of minima of a suitable energy surface in a multidimensional space of configurational coordinates. We can determine the minima by using some mathematical tools, like steepest descent, Genetic Algorithm, Genetic Algorithm and etc. Besides solved it mathematically, can we explain why the reactants change to the products (minima) analytically? In other words, can we determine the products (minima) with other means?

Thanks a lot!

[FeLiXe]

most of chemistry is not strictly mathematical
it's experience

you study mechanisms then you see how things work and you can predict new reactions withouth calculations

[Borek]

Trick is, sometimes our predictions don't work due to new/other/additional effects. In theory mathematical approach (well, numeric approach to be precise) should give always correct answer. But as for now it is only theory - we are not able to solve exact equations, we look for simplifications, effect is like with 'manual' predictions - most of the time we get it right. Sometimes we don't

[ayslam]

If I am not targeting on any particular chemicals as reactants in a chemical reaction (so I am talking about the general case), how can we predict the products? Should there be similar results as finding minima with mathematical approach? Is there any mechanism (algorithm) for the prediction?

Thanks a lot!

[FeLiXe]

if you let acid and base react you get water and salt. you don't need math for that. you just know it because it happens with pretty much every acid and base.

if you are doing transition metal complexes the situation is much more difficult. you need calculations most of the time. and there is no way around it. except for a little bit of reasoning of course.

there is always chemical reasoning. using your experience as a chemist combined with logic, helps you predict reactions.

[Mitch]

can we explain why the reactants change to the products (minima) analytically?

That is just looking at the deltaH of reaction, its not a big deal at all.