Had computational Physics today successfully modelled any reaction in chemistry?

[goldleaf]

I read a book about Feynman,saying that the chemistry may be explained by quantum physics. I got a question now: Are there anybody on the world had maken a practical numerical model which had modeled any chemistry reaction successfully from principle of Physics?

I know some chemistry people, their work are time-consuming, and usually requres a good memory.A numerical tool is meaningful, if not possible.

Is there any practical way to model a chemistry reaction from the first principle from physics?

 

[stone]

Yes, there are several examples. One of them is
K. Honkala, A. Hellman, I. N. Remediakis, A. Logadottir, A. Carlsson, S. Dahl,
C. H. Christensen, and J. K. Nørskov, Ammonia Synthesis from First-Principles
Calculations, Science 307 (2005), 555

http://www.sciencemag.org/content/307/5709/555.short

 

[ZapperZ]

I read a book about Feynman,saying that the chemistry may be explained by quantum physics. I got a question now: Are there anybody on the world had maken a practical numerical model which had modeled any chemistry reaction successfully from principle of Physics?

I know some chemistry people, their work are time-consuming, and usually requres a good memory.A numerical tool is meaningful, if not possible.

Is there any practical way to model a chemistry reaction from the first principle from physics?

Try the modeling of lead-acid battery and how it actually works

R. Ahuja et al., Phys. Rev. Lett. v.106, p.018301 (2011).

http://focus.aps.org/story/v27/st2

Zz.

 

[stone]

Try the modeling of lead-acid battery and how it actually works

R. Ahuja et al., Phys. Rev. Lett. v.106, p.018301 (2011).

http://focus.aps.org/story/v27/st2

Zz.

This one is pretty interesting and appeared last month. More physics in it as well!

 

[cgk]

A few elementary chemical reactions, like Cl + H2 -> HCl + H, can be completely simulated quantum mechanically, including the quantum nature of the nuclei (non-born-Oppenheimer effects and so on).

http://www.sciencemag.org/content/322/5901/573.abstract
http://www.sciencemag.org/content/331/6016/411.summary

For these one can directly simulate the angle-resolved reactive scattering cross sections and stuff, and get perfect agreement with measurements.

So the answer to your original question is "yes", although that maybe is not the most fascinating of chemical reactions :)

 

[DrDu]

There are two kinds of problems involved. The easier part is the calculation of the energies of the reactants and of intermediate transition states. Since the days of Feynman there have been spectacular advances and these calculations can be performed by now routinely even for very complex systems and are used to optimize e.g. catalysts.
The other type of calculations are of the type mentioned by cgk, i.e. the complete simulation of chemical reaction dynamics without recourse to simplifying models. These kind of calculations are still extremely time consuming and only possible for the simplest reactions in gas phase. On the other hand, the results from this kind of calculations are not easy to interprete even by specialists.

 

[alxm]

I'd certainly hope we can successfully model chemical reactions. Otherwise pretty much all of my research so far has been nonsense!

Now, the question is: what do you mean by 'successfully model'? As with just about any physical model, there's always room for greater detail and accuracy. As with cgk's example, the simplest reactions and chemical properties of the smallest and lightest of molecules have been calculated to within experimental accuracy. But most systems of interest (larger ones) can't currently be calculated to that level. The problem here is mainly a lack of computational power, more than a deficiency in our understanding of QM or chemistry.

So calculations aren't going to replace lab work anytime soon. But not having that level of accuracy doesn't mean you can't say anything, either. For instance, if you have an error in energy of about 5 kcal/mol (as is the case with most DFT methods), that's nowhere near accurate enough to predict chemical reaction rates, which have an exponential dependence on energy.

But what you can do, for instance, is calculate various possible reaction mechanisms and then exclude the ones that are too far from the measured value. That's basically the main 'niche' for quantum-chemical calculations today: Explaining the things you can't measure experimentally with ease, and aiding in interpreting the experimental results.

Quantum chemistry is rapidly becoming more and more significant these days. To the extent that the field is on the verge of splitting (if it hasn't already) between quantum chemists who do method development, and the quantum chemists who are mainly devoted to using the methods so solve chemical problems.

But the field hasn't reached the state where it's a "black box" where you could just put some molecules in and it'll tell you what'd happen.