Accurate Electron-Phonon Interactions from Advanced Density Functional Theory

Electron-phonon coupling (EPC) is key to understanding charge transport, band renormalization, and superconductivity in energy materials, including correlated transition-metal oxides, ferroelectric perovskites, optoelectronic semiconductors, and phonon-mediated superconductors. Although first-principles density functional theory (DFT)-based EPC calculations are used widely, their predictive power is limited by the accuracy, transferability, and efficiency of the underlying exchange-correlation functionals. These limitations become exacerbated in complex <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>d</a:mi> </a:math> - and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>f</c:mi> </c:math> -electron materials, where beyond-DFT approaches and additional corrections, such as the Hubbard <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>U</e:mi> </e:math> , are commonly invoked. Here, using the examples of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mrow> <g:mi>Co</g:mi> <g:mi mathvariant="normal">O</g:mi> </g:mrow> </g:math> and <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:mi>Ni</j:mi> <j:mi mathvariant="normal">O</j:mi> </j:mrow> </j:math> , we show how the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:msup> <m:mi>r</m:mi> <m:mn>2</m:mn> </m:msup> </m:math> SCAN density functional correctly captures strong EPC effects in transition-metal oxides without requiring the introduction of Hubbard <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi>U</o:mi> </o:math> parameters. We also find that <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:msup> <q:mi>r</q:mi> <q:mn>2</q:mn> </q:msup> </q:math> SCAN successfully describes the subtle interplay between ionic and covalent bonding, and strong EPC effects in the low-temperature rhombohedral phase of the prototypical ferroelectric <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:mrow> <s:mi>Ba</s:mi> <s:mi>Ti</s:mi> <s:mi mathvariant="normal">O</s:mi> </s:mrow> </s:math> <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"> <v:msub> <v:mi/> <v:mn>3</v:mn> </v:msub> </v:math> , without requiring Hubbard <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"> <x:mi>U</x:mi> </x:math> and intersite <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"> <z:mi>V</z:mi> </z:math> corrections. We further demonstrate the ability of <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"> <bb:msup> <bb:mi>r</bb:mi> <bb:mn>2</bb:mn> </bb:msup> </bb:math> SCAN to accurately model the EPC of the main-group semiconductor <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"> <db:mrow> <db:mi>Ga</db:mi> <db:mi>As</db:mi> </db:mrow> </db:math> and the phonon-mediated superconducting properties of <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"> <fb:mrow> <fb:mi>Mg</fb:mi> <fb:mi mathvariant="normal">B</fb:mi> </fb:mrow> </fb:math> <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"> <ib:msub> <ib:mi/> <ib:mn>2</ib:mn> </ib:msub> </ib:math> , with reliable electronic bands and phonons. Our study establishes <kb:math xmlns:kb="http://www.w3.org/1998/Math/MathML" display="inline"> <kb:msup> <kb:mi>r</kb:mi> <kb:mn>2</kb:mn> </kb:msup> </kb:math> SCAN-based EPC as a transferable, parameter-free, and computationally efficient framework for predictive material-specific modeling of EPC in energy materials, and opens a practical route toward high-throughput screening of superconductors, thermoelectrics, optoelectronic semiconductors, and oxide electrodes and catalysts.