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##

24.11 Expectation values

`EXPEC`[,[`METHOD`=]*method*][,[`TYPE`=]*type*][,*opname*]
One-electron properties in closed-shell QCISD, QCISD(T), CCD, CCSD, and DCSD can be computed by
using `EXPEC`. (the `GEXPEC` directive has no effect in this case). The following
options can be specified

`METHOD`:
*method*=`EDERIV`: Default case. Properties are obtained as analytical energy derivatives.

*method*=`XCCSD`: eXpectation-value CCSD method (with the exponential ansatz used also for bra) - see section 25.6.

*method*=`XCCSD(3)`: A simplified version of XCCSD - see section 25.6. It is also available for the local CCSD method.
`TYPE`:
*type*=`RELAX`: Compute fully relaxed properties with taking into account the orbital relaxation (default). Nonrelaxed properties are also computed and printed.

*type*=`NORELAX`: Compute properties without taking into account the orbital relaxation.
The `TYPE` option has only effect for the analytical energy derivatives.

Note that, in CCSD, the orbital relaxation effect on properties is less pronounced than, for example, in MP2. By default, only dipole moments are computed.
The syntax for operators *opname* is explained in section 6.13. See also `DM` in section 24.12, and `NATORB` in section 24.13.

** Next:** 24.12 Saving the density
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** Previous:** 24.10.2 Single-reference correlation treatments
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molpro@molpro.net 2018-07-22