Reference.Variables.expect

Variable "expect" in MATLAB/Octave version of WavePacket

This global, structured(!) variable holds expectation values of observables. Inside WavePacket, they are only used for plotting and logfile output. However, they may also be used for post-processing outside WavePacket since they contain the desired physical results from wavefunction or trajectory calculations. After running a WavePacket simulation, this information is made available in the Matlab console by simply issueing the "global expect" command.

• For time-dependent calculations using qm_propa, the index i denotes the i-th main time step.
• For time-independent calculations using qm_bound, the index i denotes the i-th calculated eigenstate.

For the observables listed in the following table, expectation values are routinely calculated in every WavePacket simulation

observable	description	cell index
pop	populations of channels	n.a.
pos	positions	spatial components
mom	momenta	spatial components
pot	potential energy	n.a.
kin	kinetic energy	n.a.
amo	additional multiplicative operators; if defined in hamilt.amo	individual AMO's

For each of the above observables of interest, WavePacket creates an object of the (generic) class +obs/@generic, containing information for each channel, as well as averaged over all channels. In particular, this class contains the following properties

property	description
cha	expectation values for each of the channels
unc	uncertainties for each of the channels
tot	total, i.e. averaged over all channels

For example, you'll find the expectation value of the third component of the position vector for the second channel for the 42nd time step (or 42nd bound state) here:

expect.pos{3}.cha{2}(42)

In addition to the above objects, the structure "expect" also holds a field "total", simply containing a time series of the total energy, i.e. averaged over all channels, obtained from the full Hamiltonian, including the contributions of coupling to external fields (which is not (yet?) included in any of the values listed above). For example, you'll find the total energy for the 42nd time step (or 42nd bound state) here:

expect.total(42)