期刊
出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.2017850118
关键词
density functional theory (DFT); symmetry breaking; jellium
资金
- NSF [DMR-1939528, DMR-1553022]
- Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0019350]
- Department of Energy, Basic Energy Sciences, through the Energy Frontier Research Center for Complex Materials from First Principles Grant [DE-SC0012575]
- Temple University
- U.S. Department of Energy (DOE) [DE-SC0019350] Funding Source: U.S. Department of Energy (DOE)
Strong correlations within a symmetry-unbroken ground-state wavefunction may manifest in approximate density functional theory as symmetry-broken spin densities or total densities, arising from soft modes of fluctuations such as spin-density or charge-density waves. An approximate density functional that breaks symmetry can be more revealing than an exact functional that does not, with examples including the stretched H-2 molecule, antiferromagnetic solids, and the static charge-density wave/Wigner crystal phase of a low-density jellium. Time-dependent density functional theory quantitatively shows that the static charge-density wave is a soft plasmon, with the frequency of a related density fluctuation dropping to zero.
Strong correlations within a symmetry-unbroken ground-state wavefunction can show up in approximate density functional theory as symmetry-broken spin densities or total densities, which are sometimes observable. They can arise from soft modes of fluctuations (sometimes collective excitations) such as spin-density or charge-density waves at nonzero wavevector. In this sense, an approximate density functional for exchange and correlation that breaks symmetry can be more revealing (albeit less accurate) than an exact functional that does not. The examples discussed here include the stretched H-2 molecule, antiferromagnetic solids, and the static charge-density wave/Wigner crystal phase of a low-density jellium. Time-dependent density functional theory is used to show quantitatively that the static charge-density wave is a soft plasmon. More precisely, the frequency of a related density fluctuation drops to zero, as found from the frequency moments of the spectral function, calculated from a recent constraint-based wavevector- and frequency-dependent jellium exchange-correlation kernel.
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