Publication date: Dec 30, 2020
Strong correlations within a symmetryunbroken groundstate wavefunction can show up in approximate density functional theory as symmetrybroken spindensities or total densities, which are sometimes observable. They can arise from soft modes of fluctuations (sometimes collective excitations) such as spindensity or chargedensity 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 H2 molecule, antiferromagnetic solids, and the static chargedensity wave/Wigner crystal phase of a lowdensity jellium. Timedependent 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 constraintbased wavevector and frequencydependent jellium exchangecorrelation kernel. This record contains all raw data used in this project. The second version contains betterconverged data for the frequency moments. The parameters used to generate this data are included in a text file. The third version includes third moment sum rule data that is more stable (a typo in the spline interpolation was rectified, see the Gitlab commit record for more detailed information), as well as expanded correlation energy per electron data. The MCP07 analytic continuation to imaginary frequencies is also more correctly treated in this new data set.
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File name  Size  Description 

4.0_moments.csv
MD5md5:c9185e51a680a36a3e514bfe4c5f8ebc

26.5 KiB  Zeroth (spectral function), first, and second frequency moments for a bulk jellium of rs = 4, using the dynamic XC MCP07 kernel 
69.0_moments.csv
MD5md5:c3520280f04c46955fefc2bc36d24a23

26.9 KiB  Zeroth (spectral function), first, and second frequency moments for a bulk jellium of rs = 69, using the dynamic XC MCP07 kernel. 
rs_4.0_third_moment_sum_rule.csv
MD5md5:36b326b5f80708b844ee2ad249764617

19.8 KiB  Comparison of the thirdfrequency moment computed directly and extracted via the known sum rule on the XC spectral function (using PW92 approximation for interacting kinetic energy). Bulk jellium, rs = 4. 
rs_69.0_third_moment_sum_rule.csv
MD5md5:ad3ff1ea34c9594c351c896a242b81a6

20.5 KiB  Comparison of the thirdfrequency moment computed directly and extracted via the known sum rule on the XC spectral function (using PW92 approximation for interacting kinetic energy). Bulk jellium, rs = 69. 
epsilon_C_MCP07.csv
MD5md5:ac8166225f6b8fd24eeee20a9d990337

4.4 KiB  Correlation energy per particle in bulk jellium using the dynamic MCP07 kernel 
epsilon_C_MCP07_static.csv
MD5md5:dd78c82251e1494bddfbd4ec1c4ea7e4

4.4 KiB  Correlation energy per particle in bulk jellium using the static MCP07 kernel 
epsilon_C_ALDA.csv
MD5md5:ad3618e10bdad1302bce161bbd74abe2

1.9 KiB  Correlation energy per particle in bulk jellium using the adiabatic local density approximation (ALDA). 
epsilon_C_RPA.csv
MD5md5:a27cea9c77fa20e51076599cb93b7fe0

6.5 KiB  Correlation energy per particle in bulk jellium using the random phase approximation (RPA) 
readme.txt
MD5md5:b16bfde0e91c95b3edd09be70abcb2fd

610 Bytes  Description of parameters needed to generate these results. Also reflected in the Gitlab repo settings.py file. 
2020.173 (version v3) [This version]  Dec 30, 2020  DOI10.24435/materialscloud:vhwc 
2020.165 (version v2)  Dec 22, 2020  DOI10.24435/materialscloud:xyj1 
2020.157 (version v1)  Dec 01, 2020  DOI10.24435/materialscloud:6tp9 