code: def seebeck_spb(eta,Lambda=0.5):
      
      from fdint import fdk
      
      return constants.k/constants.e * ((2. + Lambda) * fdk( 1.+ Lambda, eta)/ 
                   ((1.+Lambda)*fdk(Lambda, eta))- eta) * 1e+6
docs: Seebeck analytic formula in the single parabolic model