تقرير
Revealing quasi-excitations in the low-density homogeneous electron gas with model exchange-correlation kernels
| العنوان: | Revealing quasi-excitations in the low-density homogeneous electron gas with model exchange-correlation kernels |
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| المؤلفون: | Kaplan, Aaron D., Ruzsinszky, Adrienn |
| سنة النشر: | 2023 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Quantum Gases |
| الوصف: | Time-dependent density functional theory (TDDFT) within the linear response regime provides a solid mathematical framework to capture excitations. The accuracy of the theory, however, largely depends on the approximations for the exchange-correlation (xc) kernels. Away from the long-wavelength (or $q=0$ short wave-vector) and zero-frequency ($\omega=0$) limit, the correlation contribution to the kernel becomes more relevant and dominant over exchange. The dielectric function in principle can encompass xc effects relevant to describe low-density physics. Furthermore, besides collective plasmon excitations, the dielectric function can reveal collective electron-hole excitations, often dubbed ``ghost excitons.'' Beside collective excitons, the physics in the low-density regime is rich, as exemplified by a static charge-density wave that was recently found for $r_\mathrm{s} > 69$, and was shown to be associated with softening of the plasmon mode. These excitations are seen to be present in much higher density 2D HEGs, of $r_\mathrm{s} \geq 4$. In this work we perform a thorough analysis with xc model kernels for excitations of various nature. The uniform electron gas as a useful model of real metallic systems is used as a platform of our analysis. We highlight the relevance of exact constraints as we display and explain screening and excitations in the low-density region. Comment: Updated in response to reviewer report - see especially new figures in App. A, and new Apps. B and C |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2308.15392 |
| رقم الأكسشن: | edsarx.2308.15392 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |