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The material-specific electronic band structure of the electron-doped high- T c cuprate Nd1.85Ce0.15CuO4 (NCCO) is calculated in the pseudogap regime using the recently developed generalized LDA + DMFT + Σ k scheme. The LDA/DFT (density-functional theory within local density approximation) provides model parameters (hopping integral values and local Coulomb interaction strength) for the one-band Hubbard model, which is solved by the DMFT (dynamical mean-field theory). To take pseudogap fluctuations into account, the LDA + DMFT is supplied with an “external” k-dependent self-energy Σ k that describes interaction of correlated conducting electrons with nonlocal Heisenberg-like antiferromagnetic (AFM) spin fluctuations responsible for the pseudogap formation. Within this LDA + DMFT + Σ k approach, we demonstrate the formation of pronounced hot spots on the Fermi surface (FS) map in NCCO, opposite to our recent calculations for Bi2Sr2CaCu2O8 − δ (Bi2212), which have produced a rather extended region of the FS “destruction.” There are several physical reasons for this fact: (i) the hot spots in NCCO are located closer to the Brillouin zone center; (ii) the correlation length ξ of AFM fluctuations is longer for NCCO; (iii) the pseudogap potential Δ is stronger than in Bi2212. Comparison of our theoretical data with recent bulk-sensitive high-energy angle-resolved photoemission (ARPES) data for NCCO provides good semiquantitative agreement. Based on that comparison, an alternative explanation of the van Hove singularity at −0.3 eV is proposed. Optical conductivity for both Bi2212 and NCCO is also calculated within the LDA + DMFT + Δ k scheme and is compared with experimental results, demonstrating satisfactory agreement. [ABSTRACT FROM AUTHOR]

Abstract: The metal–insulator (MI) transition in quasi-one-dimensional compound V6O13 has been investigated by angle-resolved photoemission spectroscopy (ARPES) at the photon energy of  eV using synchrotron radiation and optical study below 2 eV. Along the direction, a clear Fermi cutoff and a band dispersion near are observed in the ARPES spectra. The energy distribution curves (EDC) show an opening of a gap 0.2 eV across the transition temperature  K. The ARPES at  eV is confirmed to be a bulk-sensitive spectroscopy with high resolutions in energy and momenta. [Copyright &y& Elsevier]