Line data    Source code

       1              : !!****m* ABINIT/m_lattice_verlet_mover
       2              : !! NAME
       3              : !! m_lattice_verlet_mover
       4              : !!
       5              : !! FUNCTION
       6              : !! This module contains the verlet  (NVE) lattice mover.
       7              : !!
       8              : !!
       9              : !!
      10              : !! Datatypes:
      11              : !!
      12              : !! * lattice_verlet_mover_t: defines the lattice movers
      13              : !!
      14              : !! Subroutines:
      15              : !! TODO: add this when F2003 doc style is determined.
      16              : !!
      17              : !!
      18              : !! COPYRIGHT
      19              : !! Copyright (C) 2001-2026 ABINIT group (hexu)
      20              : !! This file is distributed under the terms of the
      21              : !! GNU General Public License, see ~abinit/COPYING
      22              : !! or http://www.gnu.org/copyleft/gpl.txt .
      23              : !! For the initials of contributors, see ~abinit/doc/developers/contributors.txt .
      24              : !!
      25              : !! SOURCE
      26              : 
      27              : 
      28              : 
      29              : #if defined HAVE_CONFIG_H
      30              : #include "config.h"
      31              : #endif
      32              : 
      33              : #include "abi_common.h"
      34              : 
      35              : module m_lattice_verlet_mover
      36              :   use defs_basis
      37              :   use m_abicore
      38              :   use m_errors
      39              : 
      40              :   use m_multibinit_dataset, only: multibinit_dtset_type
      41              :   use m_abstract_potential, only: abstract_potential_t
      42              :   use m_abstract_mover, only: abstract_mover_t
      43              :   use m_lattice_mover, only: lattice_mover_t
      44              :   use m_multibinit_cell, only: mbcell_t, mbsupercell_t
      45              :   use m_random_xoroshiro128plus, only:  rng_t
      46              :   use m_hashtable_strval, only: hash_table_t
      47              : !!***
      48              : 
      49              :   implicit none
      50              : 
      51              :   private
      52              : 
      53              :   type, public, extends(lattice_mover_t) :: lattice_verlet_mover_t
      54              :    contains
      55              :      procedure :: initialize
      56              :      procedure :: finalize
      57              :      procedure :: run_one_step
      58              :   end type lattice_verlet_mover_t
      59              : 
      60              : contains
      61              : 
      62              : 
      63            3 :   subroutine initialize(self,params, supercell, rng)
      64              :     class(lattice_verlet_mover_t), intent(inout) :: self
      65              :     type(multibinit_dtset_type), target, intent(in):: params
      66              :     type(mbsupercell_t), target, intent(in) :: supercell
      67              :     type(rng_t), target, intent(in) :: rng
      68            3 :     call self%lattice_mover_t%initialize(params, supercell, rng)
      69            3 :     self%label = "Velocity Verlet lattice mover"
      70            3 :   end subroutine initialize
      71              : 
      72            3 :   subroutine finalize(self)
      73              :     class(lattice_verlet_mover_t), intent(inout) :: self
      74            3 :     call self%lattice_mover_t%finalize()
      75            3 :   end subroutine finalize
      76              : 
      77              : 
      78              :   !===================== run_one_step===============================!
      79              :   ! run one md step
      80              :   ! effpot: effective potential
      81              :   ! displacement: Should NOT be given, because it is stored in the mover already.
      82              :   ! strain: Should Not be given. Because 1) it is stored in the mover,
      83              :   !          and 2) this is a constant volume mover.
      84              :   ! spin: spin of atoms. Useful with spin-lattice coupling.
      85              :   ! lwf: lattice wannier function. Useful with lattice-lwf coupling (perhaps useless.)
      86              :   ! energy_table: energy table
      87         3002 :   subroutine run_one_step(self, effpot,displacement, strain, spin, lwf, energy_table)
      88              :     class(lattice_verlet_mover_t), intent(inout) :: self
      89              :     class(abstract_potential_t), intent(inout) :: effpot
      90              :     real(dp), optional, intent(inout) :: displacement(:,:), strain(:,:), spin(:,:), lwf(:)
      91              :     type(hash_table_t), optional, intent(inout) :: energy_table
      92              :     integer :: i
      93              :     character(len=40) :: key
      94              : 
      95              : 
      96              :     ! first half of velocity update. And full displacement update.
      97              :     ! v(t+1/2 dt) = v(t) + F/m * 1/2 dt
      98              :     ! x(t+dt) = x(t) + v(t+1/2 dt) * dt
      99     12971642 :     self%forces(:, :) =0.0
     100         3002 :     self%energy = 0.0
     101              :     call effpot%calculate( displacement=self%displacement, strain=self%strain, &
     102         7004 :          & spin=spin, lwf=lwf, force=self%forces, stress=self%stress,  energy=self%energy, energy_table=energy_table)
     103      3245162 :     do i=1, self%natom
     104              :        self%current_vcart(:,i) = self%current_vcart(:,i) + &
     105     12971642 :             & (0.5_dp * self%dt) * self%forces(:,i)/self%masses(i)
     106              :     end do
     107              :     !call self%force_stationary()
     108              : 
     109     12971642 :     self%displacement(:,:) = self%displacement(:,:)+self%current_vcart(:,:) * self%dt
     110              :     ! No need to update xcart.
     111              :     !self%current_xcart(:,:) = self%supercell%lattice%xcart(:,:) + self%displacement(:,:)
     112              : 
     113              : 
     114              :     ! second half of velocity update.
     115              :     ! v(t+dt) = v(t + 1/2 dt) + F/m * 1/2 dt
     116              :     ! NOTE: energy and forces should be initialized before every calculation!
     117         3002 :     self%energy=0.0
     118     12971642 :     self%forces(:,:)=0.0
     119              :     call effpot%calculate( displacement=self%displacement, &
     120              :          & strain=self%strain, spin=spin, lwf=lwf, force=self%forces, &
     121         7004 :          & stress=self%stress,  energy=self%energy, energy_table=energy_table)
     122      3245162 :     do i=1, self%natom
     123              :        self%current_vcart(:,i) = self%current_vcart(:,i) &
     124     12971642 :             & + (0.5_dp * self%dt) * self%forces(:,i)/self%masses(i)
     125              :     end do
     126              :     !call self%force_stationary()
     127         3002 :     call self%get_T_and_Ek()
     128         3002 :     if (present(energy_table)) then
     129         3002 :       key = 'Lattice kinetic energy'
     130         3002 :       call energy_table%put(key, self%Ek)
     131              :     end if
     132         3002 :     ABI_UNUSED_A(strain)
     133         3002 :     ABI_UNUSED_A(displacement)
     134         3002 :   end subroutine run_one_step
     135              : 
     136              : 
     137            3 : end module m_lattice_verlet_mover
     138              :