Abstract
Within density-functional theory, perturbation theory (PT) is the state-of-the-art formalism for assessing the response to homogeneous electric fields and the associated material properties, e.g., polarizabilities, dielectric constants, and Raman intensities. Here, we derive a real-space formulation of PT and present an implementation within the all-electron, numeric atom-centered orbitals electronic structure code FHI-aims that allows for massively parallel calculations. As demonstrated by extensive validation, we achieve a rapid computation of accurate response properties of molecules and solids. As an application showcase, we present harmonic and anharmonic Raman spectra, the latter obtained by combining hundreds of thousands of PT calculations with ab initio molecular dynamics. By using the PBE exchange-correlation functional with many-body van der Waals corrections, we obtain spectra in good agreement with experiment especially with respect to lineshapes for the isolated paracetamol molecule and two polymorphs of the paracetamol crystal.
Highlights
The response of molecules and solids to an applied electric field is a fundamental physical mechanism of prime importance, since it determines significant properties and spectroscopic signals, such as dielectric constants, Raman spectra, and sum-frequency generation spectra
In first-principles frameworks, these quantities are typically computed via time-dependent density-functional theory (DFT) [1, 2] or via analytical perturbation theory (PT) in either its density-functional perturbation theory (DFPT) [3,4,5,6] or coupled perturbed self-consistent field (CPSCF) formulation [7,8,9,10,11,12]
We have shown that these calculations can be systematically converged with respect to the numerical parameters used in the computation
Summary
Honghui Shang1, Nathaniel Raimbault1, Patrick Rinke2, Matthias Scheffler1, Mariana Rossi1,3 and Christian Carbogno1,3 Keywords: coupled perturbed self-consistent field method, density-functional perturbation theory, atom-centered basis functions, Original content from this homogeneous electric fields, Raman spectra, paracetamol work may be used under the terms of the Creative Commons Attribution 3.0 licence.
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