Tools related to X-ray absorption spectroscopy (XAS) calculations.

This package is developed as part of a project funded by the U.S. Department of Energy. See acknowledgment below.

Haoyue Guo ([email protected]), Matthew Carbone, Nong Artrith ([email protected]), Deyu Lu, Alex Urban ([email protected])

Install using pip

pip install --user .

Or install in editable (developer) mode with

pip install --user -e .

The package generates input files for XAS simulations with the supercell core-hole approach [1].

The following list describes the generak “workflow”:

1. Given an input atomic structure
2. All distinct absorbers are determined based on the symmetry of the structure
3. Multiplicities are determined based on the number of symmetrically equivalent absorbers
4. If requested, a supercell is created
5. VASP input files are generated for
   • A ground-state calculation without core hole
   • Core-hole potential calculations for all symmetrically distinct absorbers
6. VASP calculations are performed as usual
7. The VASP output is post-processed by
   • Alignment of the XAS lines for individual absorbers
   • Combining and broadening the XAS lines of all individual absorbers

We acknowledge financial support by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Contract No. DE-SC0012704. DFT calculations and machine-learning model construction made use of the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575 (allocation no. DMR14005). Calculations were also performed on the computational resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. We also acknowledge computing resources from Columbia University’s Shared Research Computing Facility project, which is supported by NIH Research Facility Improvement Grant 1G20RR030893-01, and associated funds from the New York State Empire State Development, Division of Science Technology and Innovation (NYSTAR) Contract C090171, both awarded April 15, 2010.

[1] F. Karsai, M. Humer, E. Flage-Larsen, P. Blaha and G. Kresse, Phys. Rev. B 98 (2018) 235205 .