of CTS and is now widely used [@Seo_2004CR; @Review_2006JPSJ; @Seo_2006JPSJ]. The observed de Haas-van Alphen oscillations in \[Ni(tmdt)$_2$\] are consistent with the tight-binding picture [@Tanaka_2004JACS]. In ref. , we proposed that the basis sets for the effective models of \[Ni(tmdt)$_2$\] and \[Au(tmdt)$_2$\] can be taken as virtual orbitals whose wave functions are parts of the relevant MO near $\epsilon_{\rm F}$, rather than the MO themselves. In this paper, we extend our theoretical approach to the newly synthesized \[Cu(tmdt)$_2$\] and seek for a systematic view of the electronic states among the isostructural family of \[$M$(tmdt)$_2$\] ($M$ = Ni, Au, and Cu).

In § \[sec2\], we set up our effective multiorbital Hubbard model and derive tight-binding parameters by fitting the results of first-principles band calculations. By considering a common set of basis functions for the three materials, a systematic view of the electronic states is achieved. Essentially, the transfer integrals providing the structures of each band are similar among the members, and orbital mixing is mostly governed by the energy difference between the $p\pi$- and $pd\sigma$-type orbitals.

Then, in § \[sec3\], by treating the on-site Coulomb interactions within MF approximation, we investigate the ground-state properties of models for \[Au(tmdt)$_2$\] and \[Cu(tmdt)$_2$\]. We 