LTBOUNDLIBXC: Difference between revisions

Revision as of 14:15, 13 January 2022

LTBOUNDLIBXC = .TRUE. | .FALSE.
Default: LTBOUNDLIBXC = .FALSE.

Description: LTBOUNDLIBXC specifies whether or not the lower bound for the Kohn-Sham kinetic-energy density $\tau _{\sigma }$ ( $\tau _{\sigma }^{\textrm {W}}<\tau _{\sigma }$ ) is enforced before $\tau _{\sigma }$ is used in a meta-GGA functional from Libxc.

The Kohn-Sham kinetic-energy density $\tau _{\sigma }$ should in principle be larger than the von Weizsäcker kinetic-energy density $\tau _{\sigma }^{\textrm {W}}=\left\vert \nabla \rho _{\sigma }\right\vert ^{2}/\left(8\rho _{\sigma }\right)$ . However, for numerical reasons this may not always be the case and can potentially lead to problems depending on the meta-GGA. If LTBOUNDLIBXC=.TRUE., then $\tau _{\sigma }=\max(\tau _{\sigma },\tau _{\sigma }^{\mathrm {W} })$ is applied before $\tau _{\sigma }$ 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 $\tau _{\sigma }=\max(\tau _{\sigma },\tau _{\sigma }^{\mathrm {W} })$ leads to very inaccurate forces and stress tensor. Therefore, by default LTBOUNDLIBXC=.FALSE..

Related Tags and Sections

LIBXC1, METAGGA

Examples that use this tag

↑ J. Sun, A. Ruzsinszky, and J. P. Perdew, Phys. Rev. Lett. 115, 036402 (2015).

[sun:prl:15-1] J. Sun, A. Ruzsinszky, and J. P. Perdew, Phys. Rev. Lett. 115, 036402 (2015).

[1]

@@ Line 1: / Line 1: @@
-{{TAGDEF|TBOUNDLIBXC|.TRUE. {{!}} .FALSE. |.FALSE.}}
+{{TAGDEF|LTBOUNDLIBXC|.TRUE. {{!}} .FALSE. |.FALSE.}}
-Description: {{TAG|TBOUNDLIBXC}} specifies whether or not the lower bound for the Kohn-Sham kinetic-energy density <math>\tau_{\sigma}</math> (<math>\tau_{\sigma}^{\textrm{W}}<\tau_{\sigma}</math>) is enforced before <math>\tau_{\sigma}</math> is used in a meta-GGA functional from Libxc.
+Description: {{TAG|LTBOUNDLIBXC}} specifies whether or not the lower bound for the Kohn-Sham kinetic-energy density <math>\tau_{\sigma}</math> (<math>\tau_{\sigma}^{\textrm{W}}<\tau_{\sigma}</math>) is enforced 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.
+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|LTBOUNDLIBXC}}=.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. Therefore, by default {{TAG|TBOUNDLIBXC}}=.FALSE..
+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|LTBOUNDLIBXC}}=.FALSE..
 == Related Tags and Sections ==
@@ Line 12: / Line 12: @@
 {{TAG|METAGGA}}
-{{sc|TBOUNDLIBXC|Examples|Examples that use this tag}}
+{{sc|LTBOUNDLIBXC|Examples|Examples that use this tag}}
 ----
 [[Category:INCAR]][[Category:XC Functionals]][[Category:metaGGA]]