The examples in this directory illustrate the use of thermo_pw to make the 
following calculations:

example01: 
what = scf       : a single scf calculation to determine the total energy.
ngeo = 1           If calculated with several images, only the root image
                   does the calculation. The others remain idle.

example02: 
what = scf_bands : a band structure calculation after a scf calculation.
ngeo = 1           This calculation produces a band structure plot.
                   If calculated with several images, only the root image
                   does the calculation. The others remain idle.

example03:
what = scf_ph    : a phonon calculation at a single q after a scf run.
ngeo = 1           This calculation computes only the frequencies and
                   displacements at a given q.
                   When calculated with several images, only the root image
                   does the scf calculation. All the images run asynchronously
                   and cooperate to calculate the phonon. The maximum number
                   of working images is the number representations, the others
                   remain idle. 
                   

example04:
what = scf_disp  : a phonon dispersion calculation after a scf run.
ngeo = 1           This calculation produces a plot of the phonon dispersions,
                   a plot of the phonon density of states, and plots of 
                   the vibrational energy, free energy, entropy, and constant 
                   volume specific heat. 
                   If calculated with several images, only the root image
                   does the scf calculation. All the images run asynchronously
                   and cooperate to calculate the phonons. The maximum number
                   of working images is the total number representations
                   (adding on all q).

example05:
what = mur_lc    : equilibrium lattice constant via Murnaghan equation.
ngeo = # of geom.  Presently only celldm(1) is changed. All the ratios and
                   angles are kept constant.
                   This calculation produces a plot of the energy as a 
                   function of the volume and a plot of the volume as a 
                   function of pressure.
                   The equilibrium T=0 lattice constant and bulk modulus 
                   are written on output.
                   If calculated with several images all the images run 
                   asynchronously and cooperate to calculate each geometry.

example06:
what = mur_lc_b  : This example computes all as above and produces a
ngeo = # of geom.  plot of the band structure at the equilibrium lattice 
                   constant.
                   If calculated with several images each image run 
                   asynchronously and calculates a different geometry.
                   The bands are calculated by only one image.

example07:
what = mur_lc_ph : This example computes all as in example05 and produces also
ngeo = # of geom.  the frequencies and displacements at a single q at the 
                   minimum of the Murnaghan.
                   If calculated with several images each image runs 
                   asynchronously and calculates a different geometry.
                   Then the root image computes the lattice constant at the
                   equilibrium geometry and finally all the images run again
                   asynchronously each one computing a different representation.

example08:
what = mur_lc_disp : This examples computes all as in example05 and
ngeo = # of geom.    a phonon dispersion at the minimum of the Murnaghan. 
                     The vibrational energy, free energy, entropy, and 
                     constant volume specific heat can be plotted at the
                     minimum of the Murnaghan.
                     If calculated with several images each image runs 
                     asynchronously and calculates a different geometry.
                     Then the root image computes the lattice constant at the
                     equilibrium geometry and finally all the images run again
                     asynchronously each one computing a different representation.

example09:
what = mur_lc_t  : This example computes a phonon dispersion at each lattice
ngeo = # of geom.  constant and allows the calculation of the zero-point 
                   energy contribution to the lattice constant and to the 
                   bulk modulus and, using the quasi harmonic approximation,
                   their dependence on the temperature. 
                   The outputs are: Dispersions at each geometry.
                   Density of states at each geometry.
                   Vibrational free energy, energy, entropy, and isochoric
                   heat capacity at each geometry.
                   Gruneisen parameters. Lattice constant and bulk modulus 
                   as a function of the temperature. Average Gruneisen 
                   parameters as a function of temperature. Isobaric heat
                   capacity as a function of temperature, isoentropic bulk
                   modulus as a function of temperature.
                   If calculated with several images each image runs 
                   asynchronously and calculates the ground state of 
                   a different geometry. Then all images are resynchronized 
                   before computing the phonon dispersions. The latter 
                   are calculated asynchronously, but the different geometries
                   are calculate sequentially and all the images are 
                   resynchronized before changing geometry.

example10:
what = scf_ke  : this example computes the total energy for several values
ngeo=1           of the kinetic energy cut-off of the wavefunctions and of the
                 charge density. The two can be specified independently or
                 a calculation at fixed dual or for several dual can be
                 specified. When images are used, each kinetic energy
                 is calculated asynchronously from the others in different
                 images.

example11:
what = scf_nk : this example computes the total energy for several values
                of the k point mesh. One can specify the number of nk, and
                the step between the first nk written on the input of pw.x
                and the others. If this is a metal also the number of values
                of the smearing degauss can be specified.

example12:
what=plot_bz : this example plots the Brillouin zone of Si and the standard
               path. It produces only the asymptote script. If you have the
               asymptote package installed, use lasymptote=.true. to produce 
               the pdf file, or give the command asy -V asy_tmp.asy to see 
               the Brillouin zone on the screen.

example13:
what=mur_lc_elastic_constants : this example computes the elastic constants 
               of silicon at the minimum of the Murnaghan equation. The
               atoms are relaxed for e44 strains.

example14:
what=scf_dos : this example computes the electron density of states 
               of silicon. The LDA bands and eigenfunctions are read by
               epsilon_tpw.x to calculate the frequency dependent
               dielectric constant of silicon (neglecting local fields).

example15:
what=scf_ph : this example computes the frequency dependent
              dielectric constant of silicon (neglecting local fields)
              using the non-self-consistent Sternheimer equation without
              sums over the empty bands. 

example16:
what=scf_ph : this example computes the frequency dependent
              dielectric constant of silicon within the TD-DFPT,
              using the self-consistent Sternheimer equation.

example17:
what=scf_ph : this example computes the inverse of the frequency dependent
              dielectric constant of aluminum at a given q within the TD-DFPT,
              using the self-consistent Sternheimer equation.

example18:
what=scf_dos : this example computes the electron density of states of aluminum
              and writes on file the electronic thermodynamic properties
              of a gas of independent electrons with the same density of
              states. (experimental)

example19:
what=scf_2d_bands : this example shows how to plot a projected density of 
             states (PBS) on a surface and the band structure of a slab on 
             top of the PBS.

example20:
what=scf_ph : this example computes the frequency dependent
              dielectric constant of silicon within the TD-DFPT,
              using a Lanczos chain.

example21:
what=scf_ph : this example computes the inverse of the frequency dependent
              dielectric constant of aluminum at a given q within the TD-DFPT,
              using a Lanczos chain.

example22:
what=elastic_constants_t: this example computes the elastic constants on the
              same set of geometries that would be used with what='mur_lc_t'.
              The files with elastic constants can be used in another run
              to modify the behavior of what='mur_lc_t' and to interpolate
              the elastic constants within the "quasi-static approximation".

example23:
what=mur_lc_t : this example computes the temperature dependent elastic
              constants within "quasi-static approximation".
              It assumes that in the directory elastic_constats many files 
              with elastic constants computed as in the example22 are 
              present (one for each geometry).
              The code computes the temperature dependent isothermal
              and adiabatic elastic constants, elastic compliaces, bulk
              modulus and compressibility. The anharmonic quantities are
              derived as explained in example09 but the comparison with
              those computed from Gruneisen parameters is added.

example24:
what=elastic_constants_qha: this example computes the elastic constants 
              as a function of temperature within the 'quasi-harmonic
              approximation' by doing the second derivatives
              of the Helmholtz free energy with respect to strain.

example25:
what=mur_lc_t : this example uses the temperature dependent elastic
              constants computed in example24 to compute the anharmonic 
              properties within the quasi-harmonic approximation. It assumes
              that the directory anhar_files contains the elastic constants 
              computed in example24.