Reference.Variables.time.steps

Variable "time.steps" in MATLAB version of WavePacket

Settable parameters

For a better understanding of the following parameters, note that there are two types of time steps. Main time steps are time intervals after which certain actions are done: expectation values are calculated, and optionally the wave function is plotted and/or saved. This has to be distinguished from the sub steps or propagation time steps which are usually much smaller. They give the time stepping (time discretization) for actually propagating the wave function using the (split-operator or other) PDE solvers implemented in qm_propa or (Runge-Kutta and related) ODE solvers implemented in qm_optimal. In contrast, the time sub steps are determined automatically (i.e. adaptively) when using the (Runge-Kutta or other) ODE solvers implemented in qm_control. (There the sub steps provided by the user are only used to plot the (usually fast) time dependence of the electric fields.)

time.main	Parameters concerning the main time steps	default
start	Starting time of the propagation in integer units of time.main.delta	0
stop	Finishing time of the propagation in integer units of time.main.delta
delta	Length of one main time step. Setting this to negative values enables backwards propagation (version 4.8.0 and later); however, note that time.main.start and time.main.stop are then given in negative time units.

time.sub	Parameters concerning the sub time steps	default
n	Number of sub time steps per main time step	1

Internal variables

time.main	Sets parameters concerning the main time steps
n	The total number of main time steps.
tot	The total simulation time.
grid	An array of all main time steps.
alpha	The calculated Kosloff alpha number (used in the Chebychev expansion).

time.sub	Sets parameters concerning the sub time steps
delta	The length of a single propagation time step.
alpha	Another variant of the Kosloff alpha number used in the Chebychev expansion.
grid	An array of all propagation time steps.
short	The same as time.sub.grid, but this goes only from the current main time step to the next.