LTBOUNDLIBXC: Difference between revisions
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The | The KS 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. in {{FILE|INCAR}}, 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|LTBOUNDLIBXC}}=.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. and Libxc should be compiled with the option <code>--disable-fhc</code> has explained [[Makefile.include#Libxc_.28optional.29|here]]. | ||
== Related | == Related tags and articles == | ||
{{TAG|LIBXC1}}, | {{TAG|LIBXC1}}, | ||
{{TAG|LIBXC2}}, | |||
{{TAG|METAGGA}} | {{TAG|METAGGA}} | ||
{{sc|LTBOUNDLIBXC|Examples|Examples that use this tag}} | {{sc|LTBOUNDLIBXC|Examples|Examples that use this tag}} | ||
== References == | |||
<references/> | |||
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[[Category:INCAR]][[Category: | [[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:meta-GGA]] |
Latest revision as of 14:43, 8 April 2022
LTBOUNDLIBXC = .TRUE. | .FALSE.
Default: LTBOUNDLIBXC = .FALSE.
Description: LTBOUNDLIBXC 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 KS 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 LTBOUNDLIBXC=.TRUE. in INCAR, 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 LTBOUNDLIBXC=.FALSE. and Libxc should be compiled with the option --disable-fhc
has explained here.