XSpectra: a density-functional-theory-based plane-wave pseudopotential code for XANES calculation
International Tables for Crystallography(2020)
摘要
The XSpectra code calculates XANES spectra at the K, L1 and L2,3 edges, including both electric dipole and quadrupole transitions. Density-functional theory and the Born–Oppenheimer approximation are used. The implementation relies on plane-wave basis sets, pseudopotentials and periodic boundary conditions. XSpectra belongs to the Quantum ESPRESSO distribution, an integrated suite of open-source computer codes for electronic structure calculations. XSpectra reads the self-consistent charge density produced by the PWscf code of the Quantum ESPRESSO distribution and acts as a post-processing tool. Core-hole effects are included by considering a supercell containing one absorbing atom, the pseudopotential of which is generated with a core hole in the appropriate core level. The all-electron final state wavefunctions are constructed using the projector augmented-wave method. The XANES cross section is calculated using the Lanczos method and a continued fraction expansion, avoiding the explicit calculation of empty states. The capabilities of the code are illustrated via selected examples.
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关键词
pseudopotential code,xanes calculation,density-functional-theory-based,plane-wave
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