Simulation of structured 4T1→6A1 emission bands of Mn2+ impurity in Zn2SiO4: A first-principle methodology

A sequential, fully first-principle theoretical study of the Mn2+ green emission bands in the Zn2SiO4:Mn2+ phosphor is presented for the first time. A combined approach is developed based on the modern periodic density-functional theory and cluster ab initio wave-function-based electronic structure methods, the linear response theory for lattice phonons, and generating function formalism of vibronic spectra within the displaced multi-mode harmonic oscillator model. We obtain fairly good agreement between the calculated low- and high-temperature emission band positions, widths, zero-phonon lines and phonon wings and the available experimental emission studies, with special emphasis on Mn2+ distribution over two non-equivalent Zn2+ sites in the Zn2SiO4 material. An interpretation for vibronic structure observed in the low-temperature emission spectrum of this phosphor is suggested based on the present first-principle study.