## File: atpstep.f90

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elkcode 5.4.24-2
 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960  ! Copyright (C) 2002-2005 J. K. Dewhurst, S. Sharma and C. Ambrosch-Draxl. ! This file is distributed under the terms of the GNU General Public License. ! See the file COPYING for license details. !BOP ! !ROUTINE: atpstep ! !INTERFACE: subroutine atpstep ! !USES: use modmain use modmpi ! !DESCRIPTION: ! Makes a geometry optimisation step and updates the current atomic positions ! according to the force on each atom. If ${\bf r}_{ij}^m$ is the position and ! ${\bf F}_{ij}^m$ is the force acting on it for atom $j$ of species $i$ and ! after time step $m$, then the new position is calculated by ! $${\bf r}_{ij}^{m+1}={\bf r}_{ij}^m+\tau_{ij}^m\left({\bf F}_{ij}^m ! +{\bf F}_{ij}^{m-1}\right),$$ ! where $\tau_{ij}^m$ is a parameter governing the size of the displacement. ! If ${\bf F}_{ij}^m\cdot{\bf F}_{ij}^{m-1}>0$ then $\tau_{ij}^m$ is ! increased, otherwise it is decreased. ! ! !REVISION HISTORY: ! Created June 2003 (JKD) !EOP !BOC implicit none ! local variables integer is,ia,ias,n real(8) t1 do is=1,nspecies do ia=1,natoms(is) ias=idxas(ia,is) ! compute the dot-product between the current and previous total force t1=dot_product(forcetot(:,ias),forcetotp(:,ias)) ! if the force is in the same direction then increase step size parameter if (t1.gt.0.d0) then tauatp(ias)=tauatp(ias)+tau0atp else tauatp(ias)=tau0atp end if ! make atomic position step atposc(:,ia,is)=atposc(:,ia,is)+tauatp(ias)*(forcetot(:,ias) & +forcetotp(:,ias)) end do end do ! each MPI process should have identical atomic positions n=3*maxatoms*maxspecies call mpi_bcast(atposc,n,mpi_double_precision,0,mpicom,ierror) do is=1,nspecies do ia=1,natoms(is) ! compute the lattice coordinates of the atomic positions call r3mv(ainv,atposc(:,ia,is),atposl(:,ia,is)) end do end do return end subroutine !EOC