Exchange–correlation corrections to lattice dynamics of simple metals, and a search for soft modes at normal and expanded volume
✍ Scribed by L. Pollack; J. P. Perdew
- Book ID
- 101252067
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 322 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0020-7608
No coin nor oath required. For personal study only.
✦ Synopsis
Using a density-based local pseudopotential, we study the effect of local field or exchange᎐correlation corrections on lattice dynamics for several simple metals Ž . the alkalis, aluminum, and lead . Turning on exchange and correlation in the dielectric function significantly reduces phonon frequencies for some metals. We consider three Ž . levels of description: the local density approximation LDA , the generalized gradient Ž . approximation GGA , and the nearly exact. Especially for the lower-density metals, the LDA linear response introduces negligible error into the phonon frequencies when exchange and correlation are treated together. This fact results from an almost complete cancellation between the nonlocalities of exchange and correlation. We find no static charge density wave in any of these metals at normal volume, even in the most favorable exchange-only case. For Na and Al at a volume about 50% bigger than normal, we find w x that a transverse phonon goes soft on the 110 zone boundary.