Density functional study of 3d-transition metal aluminides

The ground states of the 3d-metal aluminides AlSc, AlTi, AlV, AlCr, AlMn, AlFe, AlCo, AlNi, AlCu and AlZn along with their singly negatively and positively charged ions are assigned based on the results of calculations employing B3LYP density functional method. Bond lengths re, harmonic vibrational frequencies ωe, dissociation energies D0, electron affinities EA, ionization energies IE and dipole moments μ of these species are obtained. The calculated spectroscopic constants (re, ωe and D0) and ionization energies are in good agreement with the available experimental and other theoretical data except for the dissociation energies of AlCr and AlCr−. The ground state spin multiplicities of all the ions are found to differ from the spin multiplicities of the corresponding neutral parents by one. The dissociation energy of channel AlX+ → X + Al+ is lower than that of channel AlX+ → Al + X+. As for AlX−, channel AlX− → X + Al− is preferred for X = Sc, Ti, V, Cr, Mn and Zn, and channel AlX− → Al + X− is favor for X = Fe, Co, Ni and Cu. The ionization energy increases monotonically from AlSc to AlCu, while the electron affinity varies erratically across the transition metal series. The bonding patterns are also discussed.