Single-site DFT+DMFT for vanadium dioxide using bond-centered orbitals

We present a combined density-functional theory and single-site dynamical mean-field theory (DMFT) study of vanadium dioxide <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mo>(</a:mo><a:msub><a:mi>VO</a:mi><a:mn>2</a:mn></a:msub><a:mo>)</a:mo></a:math> using an unconventional set of bond-centered orbitals as the basis of the correlated subspace. <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>VO</b:mi><b:mn>2</b:mn></b:msub></b:math> is a prototypical material undergoing a metal-insulator transition (MIT), hosting both intriguing physical phenomena and the potential for industrial applications. With our choice of correlated subspace basis, we investigate the interplay of structural dimerization and electronic correlations in <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>VO</c:mi><c:mn>2</c:mn></c:msub></c:math> in a computationally cheaper way compared to other state-of-the-art methods, such as cluster DMFT. Our approach allows us to treat the rutile and M1 monoclinic <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msub><d:mi>VO</d:mi><d:mn>2</d:mn></d:msub></d:math> phases on an equal footing and to vary the dimerizing distortion continuously, exploring the energetics of the transition between the two phases. The choice of basis presented in this work hence offers a complementary view on the long-standing discussion of the MIT in <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:msub><e:mi>VO</e:mi><e:mn>2</e:mn></e:msub></e:math> and suggests possible future extensions to other similar materials hosting molecular-orbital-like states.