xc_cam.F90

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!! Copyright (C) 2025. A Buccheri
!!
!! 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"
 
module xc_cam_oct_m
  use, intrinsic :: iso_fortran_env
 
  use debug_oct_m
  use global_oct_m
  use messages_oct_m
  use namespace_oct_m
  use profiling_oct_m
 
  implicit none
  private
  public :: xc_cam_t, &
    cam_null, &
    cam_exact_exchange
 
  type xc_cam_t
    real(real64) :: omega = 0.0_real64  
    real(real64) :: alpha = 0.0_real64  
    real(real64) :: beta  = 0.0_real64  
  contains
    procedure :: is_null => xc_cam_is_null
    procedure :: print => xc_cam_print
    procedure :: as_array => xc_cam_as_array
  end type xc_cam_t
 
  type(xc_cam_t), parameter :: cam_null = xc_cam_t(0.0_real64, 0.0_real64, 0.0_real64)
 
  type(xc_cam_t), parameter :: cam_exact_exchange = xc_cam_t(0.0_real64, 1.0_real64, 0.0_real64)
 
contains
 
  pure function xc_cam_is_null(this) result(is_null)
    class(xc_cam_t), intent(in) :: this
 
    logical :: is_null
 
    is_null = all(abs([this%omega, this%alpha, this%beta]) <= m_epsilon)
 
  end function xc_cam_is_null
 
  subroutine xc_cam_print(this, namespace, msg)
    class(xc_cam_t),            intent(in) :: this
    type(namespace_t),          intent(in) :: namespace
    character(len=*), optional, intent(in) :: msg
 
    character(len=256) :: info_message
 
    push_sub(xc_cam_print)
 
    if (present(msg)) then
      info_message = msg
    else
      info_message = "CAM parameters are:"
    endif
 
    write(message(1), '(1x)')
    write(message(2), '(a)') "Info: " // trim(adjustl(info_message))
    write(message(2), '(a,f8.5)') "  alpha = ", this%alpha
    write(message(3), '(a,f8.5)') "  beta  = ", this%beta
    write(message(4), '(a,f8.5)') "  omega = ", this%omega
    call messages_info(4, namespace=namespace)
 
    pop_sub(xc_cam_print)
 
  end subroutine xc_cam_print
 
  pure function xc_cam_as_array(this) result(params)
    class(xc_cam_t), intent(in) :: this
 
    real(real64) :: params(3)
 
    params = [this%alpha, this%beta, this%omega]
 
  end function xc_cam_as_array
 
end module xc_cam_oct_m