Difference between revisions of "Ngce.m"

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{{DISPLAYTITLE:ngce.m}}
 
{{DISPLAYTITLE:ngce.m}}
Numerical generalised cumulant expansion route to the relaxation superoperator to second order, which is equivalent to Redfield theory.
+
Numerical integral route to the Redfield relaxation superoperator.
  
 
==Syntax==
 
==Syntax==
  
     R=ngce(H,dt)
+
     R=ngce(spin_system,H,dt)
  
 
==Arguments==
 
==Arguments==
  
      H    - a cell array of spin Hamiltonian commutation
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  H0 - static laboratory frame Hamiltonian commutation su-
            superoperators obtained from an MD trajectory
+
      peroperator acting in the background
 
   
 
   
      dt  - time step of the MD trajectory, seconds
+
  H1 - stochastic part of the laboratory frame Hamiltonian
 +
      commutation superoperator with a zero average, as a
 +
      K by N cell array with the following topology:
 +
 +
        {H(0) H(dt) H(2dt) ... H(Ndt);  % MD trajectory 1
 +
        H(0) H(dt) H(2dt) ... H(Ndt);  % MD trajectory 2
 +
        ............................
 +
        H(0) H(dt) H(2dt) ... H(Ndt)}; % MD trajectory K
 +
 +
      i.e. the rows are made of individual MD trajectories.
 +
 +
   dt - time step of the MD trajectory, seconds
  
 
==Outputs==
 
==Outputs==
  
 
       R    - laboratory frame relaxation superoperator
 
       R    - laboratory frame relaxation superoperator
 +
 +
==Examples==
 +
A test against the analytical relaxation superoperator is provided in examples/relaxation_theory/ngce_test.m file.
  
 
==Notes==
 
==Notes==
The trajectory must be at least five times longer than the longest correlation time expected in the system.
+
Enough trajectory points must be present to converge each integral, and enough trajectories must be present to converge the average.
  
 
==See also==
 
==See also==

Revision as of 15:37, 25 August 2018

Numerical integral route to the Redfield relaxation superoperator.

Syntax

    R=ngce(spin_system,H,dt)

Arguments

 H0 - static laboratory frame Hamiltonian commutation su-
      peroperator acting in the background

 H1 - stochastic part of the laboratory frame Hamiltonian 
      commutation superoperator with a zero average, as a
      K by N cell array with the following topology:

       {H(0) H(dt) H(2dt) ... H(Ndt);  % MD trajectory 1
        H(0) H(dt) H(2dt) ... H(Ndt);  % MD trajectory 2
        ............................
        H(0) H(dt) H(2dt) ... H(Ndt)}; % MD trajectory K

      i.e. the rows are made of individual MD trajectories.

 dt - time step of the MD trajectory, seconds

Outputs

     R    - laboratory frame relaxation superoperator

Examples

A test against the analytical relaxation superoperator is provided in examples/relaxation_theory/ngce_test.m file.

Notes

Enough trajectory points must be present to converge each integral, and enough trajectories must be present to converge the average.

See also

relaxation.m, lindbladian.m, magpump.m


Version 2.2, authors: Ilya Kuprov