quantum-espresso/PP/simple_transport

This is a collection of routines which compute transport coefficients
(Conductivity and Seebeck) using Boltzmann transport theory.

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Description of main programs:

* ef: Computation of Fermi Level for an insulating system with a given
      doping level. 

* dos: Computation of density of states using an adaptive smearing method.
       Captures Van-Hove singularities better compared to constant 
       smearing.

* fermi_int_0: Computation of transport coefficients using constant 
               scattering rate and for a range of chemical potentials.
               

* fermi_int_1: Computation of transport coefficients using constant
               scattering rate for a given Fermi Energy. Uses a 
               grid reduction algorithm (reducegrid.f90) to speed
               up the transport integrals.

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Capabilities and things to do:

* The code uses finite differences to compute band velocities. For systems
  with a fairly simple band structure, this poses no issue. For more
  complicated with structures with lots of band crossings, finite
  differences would fail. For such systems, use of packages like 
  BoltzTrap and Boltzwann are recommended. 

* The code is not tested for spin-polarized systems and with k-point
  grids that are not Gamma centered. It works for noncollinear 
  non-spin-polarized band structures. 

* The code will be extended to include calculation of transport 
  integrals using model scattering rates.