conductivity.F90

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!! Copyright (C) 2015 X. Andrade
!!
!! This program is free software; you can redistribute it and/or modify
!! it under the terms of the GNU General Public License as published by
!! the Free Software Foundation; either version 2, or (at your option)
!! any later version.
!!
!! This program is distributed in the hope that it will be useful,
!! but WITHOUT ANY WARRANTY; without even the implied warranty of
!! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!! GNU General Public License for more details.
!!
!! You should have received a copy of the GNU General Public License
!! along with this program; if not, write to the Free Software
!! Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
!! 02110-1301, USA.
!!
 
#include "global.h"
 
program conductivity
  use batch_oct_m
  use command_line_oct_m
  use global_oct_m
  use grid_oct_m
  use io_oct_m
  use ions_oct_m
  use, intrinsic :: iso_fortran_env
  use math_oct_m
  use messages_oct_m
  use namespace_oct_m
  use parser_oct_m
  use profiling_oct_m
  use space_oct_m
  use spectrum_oct_m
  use states_elec_oct_m
  use smear_oct_m
  use unit_oct_m
  use unit_system_oct_m
 
  implicit none
 
  integer :: iunit, ierr, ii, jj, iter, read_iter, ntime, nvel, ivel
  integer :: istart, iend, energy_steps, out_file
  real(real64), allocatable :: time(:), velocities(:, :)
  real(real64), allocatable :: total_current(:, :), ftcurr(:, :, :), curr(:, :)
  real(real64), allocatable :: heat_current(:,:), ftheatcurr(:,:,:), heatcurr(:,:)
  complex(real64), allocatable :: invdielectric(:, :)
  type(ions_t),     pointer :: ions
  type(space_t)     :: space
  type(spectrum_t) :: spectrum
  type(block_t)     :: blk
  type(batch_t) :: currb, ftcurrb, heatcurrb, ftheatcurrb
  real(real64) :: ww, curtime, deltat, v0
  character(len=MAX_PATH_LEN) :: ref_filename
  integer :: ref_file, time_steps_ref, kk
  real(real64), allocatable :: velcm(:), vel0(:), current(:), current_ref(:, :)
  real(real64) :: dt_ref, tt, start_time
  integer :: ifreq, max_freq
  integer :: skip, smearing
  logical :: from_forces
  character(len=120) :: header
  real(real64) :: excess_charge, qtot, javerage
 
  ! Initialize stuff
  call init_octopus_globals(serial_dummy_comm)
 
  call getopt_init(ierr)
  call getopt_end()
 
  call parser_init()
 
  call messages_init()
 
  call messages_experimental('oct-conductivity')
 
  call io_init()
  call profiling_init(global_namespace)
 
  call unit_system_init(global_namespace)
 
  space = space_t(global_namespace)
 
  call spectrum_init(spectrum, global_namespace, default_energy_step = 0.0001_real64, default_max_energy  = m_one)
 
  !%Variable ConductivitySpectrumTimeStepFactor
  !%Type integer
  !%Default 1
  !%Section Utilities::oct-conductivity_spectrum
  !%Description
  !% In the calculation of the conductivity, it is not necessary
  !% to read the velocity at every time step. This variable controls
  !% the integer factor between the simulation time step and the
  !% time step used to calculate the conductivity.
  !%End
 
  call messages_obsolete_variable(global_namespace, 'PropagationSpectrumTimeStepFactor', 'ConductivitySpectrumTimeStepFactor')
  call parse_variable(global_namespace, 'ConductivitySpectrumTimeStepFactor', 1, skip)
  if (skip <= 0) call messages_input_error(global_namespace, 'ConductivitySpectrumTimeStepFactor')
 
  !%Variable ConductivityFromForces
  !%Type logical
  !%Default no
  !%Section Utilities::oct-conductivity_spectrum
  !%Description
  !% (Experimental) If enabled, Octopus will attempt to calculate the conductivity from the forces instead of the current.
  !%End
  call parse_variable(global_namespace, 'ConductivityFromForces', .false., from_forces)
  if (from_forces) call messages_experimental('ConductivityFromForces')
 
  max_freq = spectrum_nenergy_steps(spectrum)
 
  if (spectrum%end_time < m_zero) spectrum%end_time = huge(spectrum%end_time)
 
  ions => ions_t(global_namespace)
 
  !We need the total charge
  call parse_variable(global_namespace, 'ExcessCharge', m_zero, excess_charge)
  qtot = -(ions%val_charge() + excess_charge)
 
  if (from_forces) then
 
    call messages_write('Info: Reading coordinates from td.general/coordinates')
    call messages_info()
 
    ! Opens the coordinates files.
    iunit = io_open('td.general/coordinates', global_namespace, action='read')
 
    call io_skip_header(iunit)
    call spectrum_count_time_steps(global_namespace, iunit, ntime, deltat)
    call io_close(iunit)
 
    nvel = ions%natoms*ions%space%dim
 
    safe_allocate(time(1:ntime))
    safe_allocate(velocities(1:nvel, 1:ntime))
 
    ! Opens the coordinates files.
    iunit = io_open('td.general/coordinates', global_namespace, action='read', status='old', die=.false.)
 
    call io_skip_header(iunit)
 
    ntime = 1
    iter = 1
 
    do
      read(unit = iunit, iostat = ierr, fmt = *) read_iter, curtime, &
        ((ions%pos(jj, ii), jj = 1, 3), ii = 1, ions%natoms), &
        ((ions%vel(jj, ii), jj = 1, 3), ii = 1, ions%natoms)
 
      curtime = units_to_atomic(units_out%time, curtime)
 
      if (ierr /= 0 .or. curtime >= spectrum%end_time) then
        iter = iter - 1 ! last iteration is not valid
        ntime = ntime - 1
        exit
      end if
 
      assert(iter == read_iter + 1)
 
      if (curtime >= spectrum%start_time .and. mod(iter, skip) == 0) then
 
        time(ntime) = curtime
        ivel = 1
        do ii = 1, ions%natoms
          do jj = 1, ions%space%dim
            velocities(ivel, ntime) = units_to_atomic(units_out%velocity, ions%vel(jj, ii))
            ivel = ivel + 1
          end do
        end do
 
        ntime = ntime + 1
      end if
 
      iter = iter + 1 !counts number of timesteps (with time larger than zero up to SpecEndTime)
    end do
 
    call io_close(iunit)
 
    call messages_write('      done.')
    call messages_info()
 
  else !from_forces
 
    call messages_write('Info: Reading total current from td.general/total_current')
    call messages_info()
 
    iunit = io_open('td.general/total_current', global_namespace, action='read', die=.false.)
 
    if (iunit /= -1) then
 
      call io_skip_header(iunit)
      call spectrum_count_time_steps(global_namespace, iunit, ntime, deltat)
      deltat = units_to_atomic(units_out%time, deltat)
      ntime = ntime + 1
 
      call io_skip_header(iunit)
 
      safe_allocate(total_current(1:space%dim, 1:ntime))
      safe_allocate(heat_current(1:space%dim, 1:ntime))
      safe_allocate(time(1:ntime))
 
      do iter = 1, ntime
        read(iunit, *) read_iter, time(iter), (total_current(ii, iter), ii = 1, space%dim)
        time(iter) = units_to_atomic(units_out%time, time(iter))
        do ii = 1, space%dim
          total_current(ii, iter) = units_to_atomic(units_out%length/units_out%time, total_current(ii, iter))
        end do
      end do
 
      call io_close(iunit)
 
      if (parse_is_defined(global_namespace, 'TransientAbsorptionReference')) then
        call parse_variable(global_namespace, 'TransientAbsorptionReference', '.', ref_filename)
        ref_file = io_open(trim(ref_filename)//'/total_current', action='read', status='old')
        call io_skip_header(ref_file)
        call spectrum_count_time_steps(global_namespace, ref_file, time_steps_ref, dt_ref)
        dt_ref = units_to_atomic(units_out%time, dt_ref)
        if (time_steps_ref < ntime) then
          message(1) = "The reference calculation does not contain enought time steps"
          call messages_fatal(1)
        end if
 
        if (.not. is_close(dt_ref, time(2)-time(1))) then
          message(1) = "The time step of the reference calculation is different from the current calculation"
          call messages_fatal(1)
        end if
 
        !We remove the reference
        time_steps_ref = time_steps_ref + 1
        safe_allocate(current_ref(1:space%dim, 1:time_steps_ref))
        call io_skip_header(ref_file)
        do ii = 1, time_steps_ref
          read(ref_file, *) jj, tt, (current_ref(kk, ii), kk = 1, space%dim)
        end do
        call io_close(ref_file)
        do iter = 1, ntime
          do kk = 1, space%dim
            total_current(kk, iter) = total_current(kk, iter) - current_ref(kk, iter)
          end do
        end do
        safe_deallocate_a(current_ref)
 
        start_time = spectrum%start_time
        call parse_variable(global_namespace, 'GaugeFieldDelay', start_time, spectrum%start_time)
      end if
 
      !We substract the average value, which can cause a spurious divergence at \omega=0
      !Only valid for non-metallic systems
      call parse_variable(global_namespace, 'SmearingFunction', smear_semiconductor, smearing)
      if(smearing == smear_semiconductor) then
        do kk = 1, space%dim
          javerage = m_zero
          do iter = 1, ntime
            javerage = javerage + total_current(kk, iter)
          end do
          javerage = javerage/ntime
          do iter = 1, ntime
            total_current(kk, iter) = total_current(kk, iter) - javerage
          end do
        end do
      end if
 
    else
 
      call messages_write("Cannot find the 'td.general/total_current' file.")
      call messages_new_line()
      call messages_write("Optical conductivity cannot be calculated.")
      call messages_warning()
 
      ntime = 1
      safe_allocate(total_current(1:space%dim, 1:ntime))
      safe_allocate(heat_current(1:space%dim, 1:ntime))
      safe_allocate(time(1:ntime))
 
      total_current(1:space%dim, 1:ntime) = m_zero
 
    end if
 
    iunit = io_open('td.general/total_heat_current', global_namespace, action='read', status='old', die=.false.)
 
    if (iunit /= -1) then
 
      if (ntime == 1) then
        call io_skip_header(iunit)
        call spectrum_count_time_steps(global_namespace, iunit, ntime, deltat)
        ntime = ntime + 1
      end if
 
      call io_skip_header(iunit)
 
      do iter = 1, ntime
        read(iunit, *) read_iter, time(iter), (heat_current(ii, iter), ii = 1, space%dim)
      end do
 
      call io_close(iunit)
 
    else
 
      call messages_write("Cannot find the 'td.general/heat_current' file.")
      call messages_new_line()
      call messages_write("Thermal conductivity cannot be calculated.")
      call messages_new_line()
      call messages_write("Check ConductivityFromForces to possibly compute it from forces.")
      call messages_warning()
 
      heat_current(1:space%dim, 1:ntime) = m_zero
 
    end if
  end if
 
 
  safe_allocate(curr(ntime, 1:space%dim))
  safe_allocate(heatcurr(ntime, 1:space%dim))
  safe_allocate(vel0(1:space%dim))
  vel0 = m_zero
  safe_allocate(velcm(1:space%dim))
  safe_allocate(current(1:space%dim))
 
  if (from_forces) iunit = io_open('td.general/current_from_forces', global_namespace, action='write')
 
  do iter = 1, ntime
 
    if (from_forces) then
      if (iter == 1) then
        vel0 = m_zero
        ivel = 1
        do ii = 1, ions%natoms
          do jj = 1, space%dim
            vel0(jj) = vel0(jj) + velocities(ivel, iter)/real(ions%natoms, real64)
            ivel = ivel + 1
          end do
        end do
      end if
 
      velcm = m_zero
      current = m_zero
 
      ivel = 1
      do ii = 1, ions%natoms
        do jj = 1, space%dim
          velcm(jj) = velcm(jj) + velocities(ivel, iter)/real(ions%natoms, real64)
          current(jj) = current(jj) + &
            ions%mass(ii)/ions%latt%rcell_volume*(velocities(ivel, iter) - vel0(jj))
          ivel = ivel + 1
        end do
      end do
 
      curr(iter, 1:space%dim) = vel0(1:space%dim)*qtot/ions%latt%rcell_volume + current(1:space%dim)
 
    else
      curr(iter, 1:space%dim)    = total_current(1:space%dim, iter)/ions%latt%rcell_volume
      heatcurr(iter,1:space%dim) = heat_current(1:space%dim, iter)/ions%latt%rcell_volume
    end if
 
    if (from_forces) write(iunit,*) iter, iter*deltat,  curr(iter, 1:space%dim)
 
  end do
 
  safe_deallocate_a(velcm)
  safe_deallocate_a(current)
 
 
  if (from_forces) call io_close(iunit)
 
  ! Find out the iteration numbers corresponding to the time limits.
  call spectrum_fix_time_limits(spectrum, ntime, deltat, istart, iend, max_freq)
  istart = max(1, istart)
  energy_steps = spectrum_nenergy_steps(spectrum)
 
  safe_allocate(ftcurr(1:energy_steps, 1:space%dim, 1:2))
 
  call batch_init(currb, 1, 1, space%dim, curr)
  call spectrum_signal_damp(spectrum%damp, spectrum%damp_factor, istart, iend, spectrum%start_time, deltat, currb)
 
  call batch_init(ftcurrb, 1, 1, space%dim, ftcurr(:, :, 1))
  call spectrum_fourier_transform(spectrum%method, spectrum_transform_cos, spectrum%noise, &
    istart, iend, spectrum%start_time, deltat, currb, spectrum%min_energy, spectrum%max_energy, &
    spectrum%energy_step, ftcurrb)
  call ftcurrb%end()
 
  call batch_init(ftcurrb, 1, 1, space%dim, ftcurr(:, :, 2))
  call spectrum_fourier_transform(spectrum%method, spectrum_transform_sin, spectrum%noise, &
    istart, iend, spectrum%start_time, deltat, currb, spectrum%min_energy, spectrum%max_energy, &
    spectrum%energy_step, ftcurrb)
 
  call ftcurrb%end()
  call currb%end()
 
 
  !and print the spectrum
  iunit = io_open('td.general/conductivity', global_namespace, action='write')
 
 
  write(unit = iunit, iostat = ierr, fmt = '(a)') &
    '###########################################################################################################################'
  write(unit = iunit, iostat = ierr, fmt = '(8a)')  '# HEADER'
  write(unit = iunit, iostat = ierr, fmt = '(a,a,a)') &
    '#  Energy [', trim(units_abbrev(units_out%energy)), '] Conductivity [a.u.] ReX ImX ReY ImY ReZ ImZ'
  write(unit = iunit, iostat = ierr, fmt = '(a)') &
    '###########################################################################################################################'
 
  v0 = norm2(vel0(1:space%dim))
  if (.not. from_forces .or. v0 < epsilon(v0)) v0 = m_one
 
  if (.not. from_forces .and. parse_is_defined(global_namespace, 'GaugeVectorField')) then
    if (parse_block(global_namespace, 'GaugeVectorField', blk) == 0) then
      do ii = 1, space%dim
        call parse_block_float(blk, 0, ii - 1, vel0(ii))
      end do
      call parse_block_end(blk)
    end if
    vel0(1:space%dim) = vel0(1:space%dim) / p_c
    v0 = norm2(vel0(1:space%dim))
  end if
 
 
  do ifreq = 1, energy_steps
    ww = spectrum%energy_step*(ifreq - 1) + spectrum%min_energy
    write(unit = iunit, iostat = ierr, fmt = '(7e20.10)') units_from_atomic(units_out%energy, ww), &
      transpose(ftcurr(ifreq, 1:space%dim, 1:2)/v0)
  end do
 
  call io_close(iunit)
 
 
  !Compute the inverse dielectric function from the conductivity
  ! We have \chi = -i \sigma / \omega
  ! and \epsilon^-1 = 1 + 4 \pi \chi
  safe_allocate(invdielectric(1:space%dim, 1:energy_steps))
  do ifreq = 1, energy_steps
    ww = max((ifreq-1)*spectrum%energy_step + spectrum%min_energy, m_epsilon)
 
    invdielectric(1:space%dim, ifreq) = (vel0(1:space%dim) + m_four * m_pi * &
      cmplx(ftcurr(ifreq, 1:space%dim, 2),-ftcurr(ifreq, 1:space%dim, 1), real64) / ww) / v0
 
  end do
 
  out_file = io_open('td.general/inverse_dielectric_function_from_current', global_namespace, action='write')
  select case (space%dim)
  case (1)
    write(header, '(3a15)') '#        energy', 'Re x', 'Im x'
  case (2)
    write(header, '(5a15)') '#        energy', 'Re x', 'Im x', 'Re y', 'Im y'
  case (3)
    write(header, '(7a15)') '#        energy', 'Re x', 'Im x', 'Re y', 'Im y', 'Re z', 'Im z'
  end select
  write(out_file,'(a)') trim(header)
  do ifreq = 1, energy_steps
    ww = (ifreq-1)*spectrum%energy_step + spectrum%min_energy
    select case (space%dim)
    case (1)
      write(out_file, '(3e15.6)') ww,                                        &
        real(invdielectric(1, ifreq), real64), aimag(invdielectric(1, ifreq))
    case (2)
      write(out_file, '(5e15.6)') ww,                                        &
        real(invdielectric(1, ifreq), real64), aimag(invdielectric(1, ifreq)), &
        real(invdielectric(2, ifreq), real64), aimag(invdielectric(2, ifreq))
    case (3)
      write(out_file, '(7e15.6)') ww,                                        &
        real(invdielectric(1, ifreq), real64), aimag(invdielectric(1, ifreq)), &
        real(invdielectric(2, ifreq), real64), aimag(invdielectric(2, ifreq)), &
        real(invdielectric(3, ifreq), real64), aimag(invdielectric(3, ifreq))
    end select
  end do
  call io_close(out_file)
 
  safe_deallocate_a(ftcurr)
  safe_deallocate_a(invdielectric)
 
 
!!!!!!!!!!!!!!!!!!!!!
  if (from_forces) then
    safe_allocate(ftheatcurr(1:energy_steps, 1:space%dim, 1:2))
 
    ftheatcurr = m_one
 
    call batch_init(heatcurrb, 1, 1, space%dim, heatcurr)
 
    call spectrum_signal_damp(spectrum%damp, spectrum%damp_factor, 1, ntime, m_zero, deltat, heatcurrb)
 
    call batch_init(ftheatcurrb, 1, 1, space%dim, ftheatcurr(:, :, 1))
    call spectrum_fourier_transform(spectrum%method, spectrum_transform_cos, spectrum%noise, &
      1, ntime, m_zero, deltat, heatcurrb, spectrum%min_energy, spectrum%max_energy, spectrum%energy_step, ftheatcurrb)
    call ftheatcurrb%end()
 
    call batch_init(ftheatcurrb, 1, 1, space%dim, ftheatcurr(:, :, 2))
    call spectrum_fourier_transform(spectrum%method, spectrum_transform_sin, spectrum%noise, &
      1, ntime, m_zero, deltat, heatcurrb, spectrum%min_energy, spectrum%max_energy, spectrum%energy_step, ftheatcurrb)
    call ftheatcurrb%end()
 
    call heatcurrb%end()
 
 
    !and print the spectrum
    iunit = io_open('td.general/heat_conductivity', global_namespace, action='write')
 
 
    write(unit = iunit, iostat = ierr, fmt = '(a)') &
      '###########################################################################################################################'
    write(unit = iunit, iostat = ierr, fmt = '(8a)')  '# HEADER'
    write(unit = iunit, iostat = ierr, fmt = '(a,a,a)') &
      '#  Energy [', trim(units_abbrev(units_out%energy)), '] Conductivity [a.u.] ReX ImX ReY ImY ReZ ImZ'
    write(unit = iunit, iostat = ierr, fmt = '(a)') &
      '###########################################################################################################################'
 
    v0 = norm2(vel0(1:space%dim))
    if (.not. from_forces .or. v0 < epsilon(v0)) v0 = m_one
 
    do ifreq = 1, energy_steps
      ww = spectrum%energy_step*(ifreq - 1) + spectrum%min_energy
      write(unit = iunit, iostat = ierr, fmt = '(7e20.10)') units_from_atomic(units_out%energy, ww), &
        transpose(ftheatcurr(ifreq, 1:space%dim, 1:2)/v0)
      !print *, ifreq, ftheatcurr(ifreq, 1:3, 1:2)
    end do
 
    call io_close(iunit)
 
    safe_deallocate_a(ftheatcurr)
  end if
!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 
  safe_deallocate_a(vel0)
  safe_deallocate_p(ions)
 
  safe_deallocate_a(total_current)
  safe_deallocate_a(heat_current)
  safe_deallocate_a(curr)
  safe_deallocate_a(heatcurr)
  safe_deallocate_a(time)
 
  call profiling_end(global_namespace)
  call io_end()
  call messages_end()
 
  call parser_end()
  call global_end()
 
end program conductivity
 
!! Local Variables:
!! mode: f90
!! coding: utf-8
!! End: