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Figure 1
Electron densities as calculated with VASP (full lines) and QE (dashed lines) along the Cl—Cl (top), Na—Na (middle) and Na—Cl (bottom) internuclear axes in the NaCl crystal. Different DFAs are color coded: LDA in purple, PBE in green and PW91 in black. Distances are measured from the left nucleus of each pair. The right nucleus of the pair is located at the first- (Na—Cl) or second-neighbor distance (Na—Na, Cl—Cl), at 5.28 and 7.47 a.u., respectively. Notice that several PBE and PW91 curves, particularly along the Na—Cl line, mostly overlap.

IUCrJ
Volume 12| Part 3| May 2025|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252525001721