LTBOUNDLIBXC: Difference between revisions
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The Kohn-Sham kinetic-energy density <math>\tau_{\sigma}</math> should in principle be larger than the von Weizsäcker kinetic-energy density <math>\tau_{\sigma}^{\textrm{W}}=\left\vert\nabla\rho_{\sigma}\right\vert^{2}/\left(8\rho_{\sigma}\right)</math>. However, for numerical reasons this may not always be the case and can potentially lead to problems depending on the meta-GGA. If {{TAG|TBOUNDLIBXC}}=.TRUE., then <math>\tau_{\sigma}=\max(\tau_{\sigma},\tau_{\sigma}^{\mathrm{W}})</math> is applied before <math>\tau_{\sigma}</math> is used in a meta-GGA functional from Libxc. | The Kohn-Sham kinetic-energy density <math>\tau_{\sigma}</math> should in principle be larger than the von Weizsäcker kinetic-energy density <math>\tau_{\sigma}^{\textrm{W}}=\left\vert\nabla\rho_{\sigma}\right\vert^{2}/\left(8\rho_{\sigma}\right)</math>. However, for numerical reasons this may not always be the case and can potentially lead to problems depending on the meta-GGA. If {{TAG|TBOUNDLIBXC}}=.TRUE., then <math>\tau_{\sigma}=\max(\tau_{\sigma},\tau_{\sigma}^{\mathrm{W}})</math> is applied before <math>\tau_{\sigma}</math> is used in a meta-GGA functional from Libxc. | ||
However, according to tests, for some of the most common meta-GGA functionals like SCAN{{cite|sun:prl:15}} a violation of the lower bound is technically not a problem and, furthermore, applying <math>\tau_{\sigma}=\max(\tau_{\sigma},\tau_{\sigma}^{\mathrm{W}})</math> leads to very inaccurate forces and stress tensor. | However, according to tests, for some of the most common meta-GGA functionals like SCAN{{cite|sun:prl:15}} a violation of the lower bound is technically not a problem and, furthermore, applying <math>\tau_{\sigma}=\max(\tau_{\sigma},\tau_{\sigma}^{\mathrm{W}})</math> leads to very inaccurate forces and stress tensor. Therefore, by default {{TAG|TBOUNDLIBXC}}=.FALSE.. | ||
== Related Tags and Sections == | == Related Tags and Sections == | ||
Revision as of 19:23, 12 January 2022
TBOUNDLIBXC = .TRUE. | .FALSE.
Default: TBOUNDLIBXC = .FALSE.
Description: TBOUNDLIBXC specifies whether or not the lower bound for the Kohn-Sham kinetic-energy density () is enforced before is used in a meta-GGA functional from Libxc.
The Kohn-Sham kinetic-energy density should in principle be larger than the von Weizsäcker kinetic-energy density . However, for numerical reasons this may not always be the case and can potentially lead to problems depending on the meta-GGA. If TBOUNDLIBXC=.TRUE., then is applied before is used in a meta-GGA functional from Libxc.
However, according to tests, for some of the most common meta-GGA functionals like SCAN[1] a violation of the lower bound is technically not a problem and, furthermore, applying leads to very inaccurate forces and stress tensor. Therefore, by default TBOUNDLIBXC=.FALSE..