If yes then please give me the reference paper..

binding energy of what? van der Waals pair? protein–antibody complex?

Ulrich, i'm here talking about Binding Energy of the addition of an extra atom in the cluster. Is there any method to calculate it by using its IR/Raman/UV?

Thanks

What kind of cluster? Argon? Platinum? How many atoms?

With small molecules, UV absorption spectra usually consist of a series of vibrational peaks, followed by a continuum where dissociation sets in. So the wavelength at which the continuum absorption starts indicates the dissociation energy D_0. But whether this will work for your problem I cannot say; it depends on the cluster size and the nature of the bonds between the atoms.

Kapil,

Using a method like DFT you can compute the energy of binding of an extra atom to the cluster. Or you could compute the IR and UV spectra of the cluster. (IR using harmonic vibrational frequencies; UV using time-dependent DFT). But I do not know of any way to compute the binding energy based on the specta. There does not seem to be any systematic correlation between the two

Thanks Ulrich, i was talking about germanium clusters(Size is less then 15 atoms).

can you give me any reference of your comment (Size and nature of bonds dependence), i already try to found but didnt get any. Please if you can. Thanks again.

Thanks You too George, for bulk material, i think its possible ( i'm not sure, some of my friend tells me a little but i dont have any reference of it) but for cluster, i dont know. I'm also trying to search by the help of TD-DFT.

You can use any textbook on physical chemistry as a reference for my comment (e.g., P. Atkins, “Physical Chemistry”). But I am not sure whether dissociation can be seen in the UV spectrum of a Ge15 cluster. That has so many spectral lines that the spectrum probably looks continuous anyway.

I think that you can find some information in “From Molecular Vibrations to Bonding, Chemical Reactions, and Reaction Mechanism”, Cremer, Dieter, Kraka, Elfi; Current Organic Chemistry; 2010, Vol. 14 Issue 15, p1524

I would be very interested if somebody could post a summary of the method, since I dont have full text access.

One practical matter to consider. If you want to know the binding of, say, the 15th Ge atom to a cluster of 14, it is my experience that it's a lot faster to do geometry optimization of both Ge14 and Ge15 than to compute the IR or UV of Ge15 using DFT.

Can you explain it Mr. George? Sorry for late reply, i didn't get the notification of your answer.

Thanks Svetlana and Ulrich, for help.

Kapil,

As I understand the research problem, you want to know the binding energy of adding another atom to the cluster, is that correct? Please excuse me if I go into too much detail, but I want to be sure to explain clearly.

Let's say, for example, you want the energy of adding a 5th Ge to Ge4 cluster. Using DFT, this would be calculated as delta_E = E(Ge5) - E(Ge4). You would peform a geometry optimzation of Ge4 and get the total energy. Then add the 5th Ge and do an optimization for Ge5. Then you take the difference. This is a very straight-forward calculation and gives the 'right' answer, at least within the DFT approximation.

Your original question was wether you could determine the same quantity from spectroscopy. I am not aware of any way to do that. You can use TD-DFT to compute the UV/visible spectrum of the clusters, but this will not give you the delta_E. If you are using DFT is would be quicker to do the optimziation of Ge4 and Ge5 than to compute the UV spectrum.