Atomic Structure of Glassy GeTe₄ as a Playground to Assess the Performances of Density Functional Schemes Accounting for Dispersion Forces

Abstract

The atomic structure of glassy GeTe 4 is obtained in the framework of first-principles molecular dynamics by considering five different approaches for the description of the electronic structure within density functional theory. Among these schemes, one is not corrected by the account of the dispersion forces and it is based on the BLYP exchange correlation (XC) functional, while all the others are intended to account for the dispersion forces according to different theoretical strategies. In particular, by maintaining the BLYP expression for the 1 XC functional, two of them (BLYP-D2 and BLYP-D3) exploit the Grimme expressions for the dispersion forces, while the fourth scheme is based on the Maximally Localized Wannier functions (MLWF). Finally, we also considered the rVV10 functional constructed to include seamlessly the dispersion part. Our results point out the better performances of the BLYP-D3 and MLWF in terms of comparison with experimental data for the total pair correlation functions, BLYP-D2 and rVV10 being closer to the uncorrected BLYP data. The implications of such findings are discussed by considering the overall limited impact of dispersion forces on the atomic structure of glassy GeTe 4 .

Alteration of structural, electronic, and vibrational properties of amorphous GeTe by selenium substitution: An experimentally constrained density functional study

“…It should be noted that the fraction of such Ge-Ge bonds depends on the chosen electronic scheme 51 , an increased metallic character leading to a reduction of such defects in lighter chalcogenides. For the amorphous Tellurides, different simulation schemes have also emphasized the sensitivity of DFT electronic models on the Ge-Ge statistics 52 , but weak differences are found in Ge-Ge correlations between DFT-D2 and DFT-D3 schemes 53 .…”

Hierarchical Self-Assembly and Conformation of Tb Double-Decker Molecular Magnets: Experiment and Molecular Dynamics

“…This van der Waals correction was preferred to that of D3, which proved to be responsible for parasitic effects that even lead to a non-physical phase separation in condensed matter systems [26]. In fact, except for D3, a similarity in performance is found for D2, rVV10 and several others [27]. Core-valence interactions were described by norm-conserving Troullier-Martins [28] pseudopotentials (PPs) for N, C, and H, while for Tb we make use of a Goedecker-Teter-Hutter [29] semicore PP.…”

Impact of structural short‐range order and tetrahedral germanium on electronic and dielectric properties in phase‐change materials

“…Such methods are used, for example, to determine, dispersive interactions of materials 59,60 including tellurides. 61 The partial dipole moment 𝝁 𝑖 of a given atom 𝑖 can be defined from the ion and the positions r𝑤 𝑛 of the MLWF centers by assuming that the electronic charge is concentrated in point charges located on such centers:…”

“…\end{eqnarray}$$Next, we build on the atomic‐based polarization theory 56 which establishes a link 57,58 between MLWF centers and calculated dipole moments of ions in molecules or molecular networks. Such methods are used, for example, to determine, dispersive interactions of materials 59,60 including tellurides 61 . The partial dipole moment $${\bm \mu}^i$$ of a given atom i can be defined from the ion and the positions $$\bar{\bf r}_n^w$$ of the MLWF centers by assuming that the electronic charge is concentrated in point charges located on such centers: $$$$\begin{eqnarray} {{\bm \mu}}^i={{\bm \mu}}_I^i+{{\bm \mu}}_e^i=Z_i{\bm R}_i-2\sum \limits _{n\in i}\bar{\bf r}_n^w, \end{eqnarray}$$$$where $$Z_i$$ and $${\bf R}_i$$ are the ionic charge and position of ion i , and the sum over $$n\in i$$ includes all the MLWF whose center is localized in the vicinity of $${\bf R}_i<r_m$$.…”