Anti-adiabatic

Note that the result m jm obtained through (25) does not depend on the value t in the strong-coupling and/or anti-adiabatic region. 

By comparing the result of w /w for the infinite-site system obtained by VED [96] (see. Fig. 2), we are confident that the two-site calculation provides a reasonably good result for m /m in the whole range of g at least in the anti-adiabatic region of t/a>o. The relevance of the two-site calculation has also been seen in the Holstein model [78]. Thus we can expect that the same is true for the r (g) t JT polaron. In Fig. 3, we show the result of m/m for the T (g) r system solid curve) which is obtained in the anti-adiabatic region by implementing an... 

Fig. 2 Inverse of the polaron mass enhancement factor, m/m, as a function of for the T (8) a (HP Holstein polaron) and the (8) e JT polaron. In the latter, the result in the infinite chain d = 1) is compared with that in the two-site system as weU as the analytic result in (26). The anti-adiabatic condition of (Uo// = 5 is assumed...

Fig. 3 Inverse of the mass enhancement factor, mim, as a function of g

In addition to the Coulomb interaction, the phonon-mediated interactions C/ph work on the electrons. In the weak-coupling and anti-adiabatic region, the lowest-order perturbation calculation provides C/ph = J2j with obtained as... 

Anti-adiabatic State - Ground Electronic State of Superconductors... 

Moreover, shift of the ACP substantially increases the density of states (DOS) at FL, HaiEp) = d /dk)p, and induces corresponding decrease of effective electron velocity d /dk)Ep of fluctuating band in this region of k-space. Physically, it represents the system transition from adiabatic (0Ep, or even to a strongly anti-adiabatic state with (O Ep. This effect has crucial theoretical impact. Not only is the ME approximation not valid (impossible to calculate non-adiabatic vertex corrections which represent off-diagonal corrections to the adiabatic ground state), but the adiabatic BOA itself does not hold. 

---