The mp-expectation command calculates the expectation value of an operator with finite support. The wavefunction can be finite, infinite, or infinite-boundary.
Synopsis
mp-expectation [options] <psi> <operator> [psi2]
calculates {$\bigbraket{\mbox{psi}}{\mbox{operator}}{\mbox{psi2}}$}
The operator must be defined over a finite range of lattice sites, it is not possible to use mp-iexpectation to evaluate TriangularMPO's or ProductMPO's as these have infinite support.
For infinite wavefunctions, it is not possible to calculate mixed expectation values where psi2 is different to psi1.
Options
--help
show help message
-r, --real
display the real part of the result
-i, --imag
display the imaginary part of the result
If none of --real or --imag is specified, the default is to show both the real and imaginary parts.
Examples
- local magnetization at site 5
mp-expectation psi lat:"Sz(5)"
- correlations of an SU(2) spin chain
mp-expectation psi lat:"inner(S(0),S(1))"
See also
- To calculate expectation values of TriangularMPO's, see MpIMoments
- To calculate expectation values of ProductMPO's, see MpIOverlap
