View source for Deer 4p soft deer.m

{{DISPLAYTITLE:deer_4p_soft_deer.m}} __NOTOC__
Four-pulse DEER/PELDOR pulse sequence. The sequence uses soft pulses computed with the Fokker-Planck formalism.

==Syntax==

     echo_stack=deer_4p_soft_deer(spin_system,parameters,H,R,K)

==Parameters==
 
    parameters.pulse_frq  - frequencies for the four 
                            pulses, Hz
 
    parameters.pulse_pwr  - power levels for the four
                            pulses, rad/s
 
    parameters.pulse_dur  - durations for the four
                            pulses, seconds
 
    parameters.pulse_phi  - initial phases for the four 
                            pulses, radians
 
    parameters.pulse_rnk  - Fokker-Planck ranks for the
                            four pulses
 
    parameters.p1_p2_gap  - time between the end of the 
                            first and the start of the
                             second pulse, seconds
 
    parameters.p2_p4_gap  - time between the end of the 
                            second the start of the third
                            pulse, seconds
 
    parameters.p3_nsteps  - number of third pulse posi-
                            tions in the interval between
                            the first echo and the fourth
                            pulse
 
    parameters.echo_time  - time to sample around the ex-
                            pected second echo position
 
    parameters.echo_npts  - number of points in the second
                            echo discretization
 
    parameters.rho0       - initial state
 
    parameters.coil       - detection state
 
    parameters.method     - soft puse propagation method,
                            'expv' for Krylov propagation,
                            'expm' for exponential propa-
                            gation, 'evolution' for Spin-
                            ach evolution function
 
   H  - Hamiltonian matrix, received from context function
 
   R  - relaxation superoperator, received from context function
 
   K  - kinetics superoperator, received from context function

==Outputs==

    echo_stack  - DEER echo stack, a matrix with p3_nsteps echoes
                  with echo_npts points each

==Examples==
A number of complete examples for two- and three-electron systems are given in examples/esr_solids folder. A good way to proceed (soft_4_pulse_deer_2e.m example file) is to look at how the pulses affect the system:

[[File:pulse_effect_4p.png]]

then to inspect the echo stack as a function of the pump pulse position:

[[File:deer_echo_stack_4p.png]]

and finally to inspect the principal components of the echo stack. The most prominent component is the DEER trace, the other components come from the finite size of the spherical integration grid.

[[File:deer_echo_4p.png]] [[File:deer_trace_4p.png]]

==Notes==
# For the method, start with 'expm', change to 'expv' if the calculation runs out of memory, and use 'evolution' as the last resort.
# Simulated echoes tend to be sharp and hard to catch because simulation does not have distributions in experimental parameters. Fourier transforming the echo prior to integration is recommended.
# The time in the DEER trace refers to the second pulse insertion point, after end of first pulse.

==See also==
[[deer_3p_hard_echo.m]], [[deer_3p_hard_deer.m]], [[deer_analyt.m]], [[eseem.m]], [[oopeseem.m]], [[deer_4p_soft_hole.m]], [[deer_4p_soft_diag.m]], [[deer_3p_soft_deer.m]], [[deer_3p_soft_hole.m]], [[deer_3p_soft_diag.m]], [[endor_cw.m]], [[endor_davies.m]], [[endor_mims.m]], [[endor_mims_echo.m]], [[endor_mims_ideal.m]], [[fieldsweep.m]], [[hyscore.m]], [[rapidscan.m]], [[ridme.m]], [[rydmr_exp.m]], [[sifter.m]], [[Built-in_experiments]]

''Version 2.4, authors: [[Ilya Kuprov]]''