System-environment coupling parameters

The system-environment coupling is based on the Drude spectral density

$$J_a(\omega)=2\lambda_a\gamma_a\omega/(\omega^2+\gamma_a^2).$$ (24)

Diagonal (independent) coupling, i.e. $F_a={{\left\vert a \right>}{\left< a \right\vert}}$ and $M=N$, is assumed unless DiagonalCouplingIndices or CorrelatedCouplingTerms are specified.

• NumCouplingTerms $<$ $M$ $>$
  Acceptable Values: positive integers
  Default Value: 0
  Description: Specifies the number of system-bath coupling terms.
  Example line(s):
  NumCouplingTerms=2
  
• lambda $<$ $\lambda_a$ $>$
  Acceptable Values: $M$ real values
  Default Value: None
  Description: Specifies the reorganization energy $\lambda_a$ associated with each coupling term $F_a$. Units are cm$^{-1}$
  Example line(s):
  lambda:
  100.,50.0
  
• gamma $<$ $\gamma_a$ $>$
  Acceptable Values: $M$ real values
  Default Value: None
  Description: Specifies the response frequency $\gamma_a$ associated with each coupling term $F_a$. Units are ps$^{-1}$
  Example line(s):
  gamma:
  10,10
  
• DiagonalCouplingIndices $<$ $i_a$ $>$
  Acceptable Values: $M$ non-negative integers
  Default Value: None
  Description: Specifies the state ${\left\vert i_a \right>}$ to which the term $F_a$ couples. Note: state numbering starts from 0.
  Example line(s):
  #For NumStates=2 and NumCouplingTerms=4
  DiagonalCouplingIndices:
  0,0,1,1
  
• CorrelatedCouplingTerms $<$ $f_{ai}$ $>$
  Acceptable Values: $M\times N$ real values
  Default Value: None
  Description: Specifies each system-environment coupling $F_a = \sum_i f_{ai}{{\left\vert i \right>}{\left< i \right\vert}}$.
  Example line(s):
  #For NumStates=2 and NumCouplingTerms=3
  CorrelatedCouplingTerms:
  1,0
  0,1
  0.7071,-0.7071