Having seen this question open for a while, I thought I might respond with my thoughts on this. Perhaps I have misunderstood the question (hence I didn't respond right away); if so, please do clarify.

I think you may have some trouble finding a database containing this information simply because all of the metals in the series that you mention are just that - metallic, i.e. they have a density of states at the Fermi level, and so are electrical conductors. It would therefore be completely meaningless to speak of a band-gap, as there isn't one. If you look at the website webelements, for example (http://www.webelements.com/), and read the pages for each of the elements you are interested in, you will see that all of them are classified as metallic and have an electrical resistivity of something of the order of 10-8 Ωm, i.e. very low resistivity, indicating metallic character.

I would have thought that this point is fairly obvious, hence my reluctance to respond, and my concern that I may have misunderstood your question. Even in writing this message on my computer, I have made use of the metallic nature of copper, an element listed in your series. So please, if I have misunderstood something, do respond and clarify this, and I would be more than happy to offer my thoughts on this.

Dear Michael,

First of all thank you for the reply. In fact you've understood my question correctly. Actually I was well aware about their metallic character but i was hoping not all of them must be equally metallic. My research field usually related to small metal clusters and they behave a lot different than bulk material. Initially I needed the database to compare the HOMO-LUMO gap of transition metal clusters to that with the band gap of bulk. I knew for most of them the band gap will not exists but I was looking forward that there must be a way to qualitatively tell that which one is more metallic than others so that I can compare with my results. After you answer I'm thinking now that I should put the question in other way so that it'll be less confusing. Anyway this question is not relevant for my research anymore. Thanks again for clarifying my confusion.

Hi Turbasu,

thanks for clarifying your problem. I'm still not sure what you mean when you suggest that the different metals would not be equally metallic. To me, something is metallic, or it isn't, depending on whether it does or does not have a density of states at the Fermi level (the exception to this being Mott-Hubbard insulators, where inter-electron repulsions in materials with a narrow, partially-filled highest energy band cause this deviation from "normal" behaviour predicted by standard band theory). Do you mean that different metals might exhibit different electrical properties, such as electrical conductivity, that we associate with metallic behaviour?

I am not and expert on clusters, but I agree that it could certainly be possible for clusters to exhibit an electronic structure that is markedly different from their bulk metal counterparts. However, I am not convinced that there would be a bulk quantity that would directly correspond with band gaps that you may have observed for metal clusters. Perhaps simply considering the band-gap for your clusters as a function of the proportion of d-band filling in the bulk metal would be an option. As far as I can see, this is the main difference between the bulk metals you are considering (some have more or less of their d-band filled than others), so if you do observe a trend in your band-gaps, perhaps this could be related.

Anyway, I wish you all the best with your research, I hope my comments have been helpful. Feel free to respond if there is anything that I have said that is unclear.