SpECTRE
v2023.10.11

Conjugate momentum to the spacetime metric. More...
#include <Tags.hpp>
Public Types  
using  type = tnsr::aa< DataType, Dim, Frame > 
Conjugate momentum to the spacetime metric.
If \( \psi_{ab} \) is the spacetime metric, and \( N \) and \( N^i \) are the lapse and shift respectively, then we define \( \Pi_{ab} = \frac{1}{N} ( \partial_t \psi_{ab} + N^{i} \Phi_{iab} ) \) where \(\Phi_{iab}\) is the variable defined by the tag Phi.