Chimie Théorique » Opt'n Path

! This subroutine checks that the required step fulfills some conditions:

! v1.0

! Only valence angles are checked to remain in to 0:Pi range.

SUBROUTINE Check_step(Coord,Nat,NCoord,GeomOld,Step)

!----------------------------------------------------------------------

!  Copyright 2003-2014 Ecole Normale Supérieure de Lyon, 

!  Centre National de la Recherche Scientifique,

!  Université Claude Bernard Lyon 1. All rights reserved.

!

!  This work is registered with the Agency for the Protection of Programs 

!  as IDDN.FR.001.100009.000.S.P.2014.000.30625

!

!  Authors: P. Fleurat-Lessard, P. Dayal

!  Contact: optnpath@gmail.com

!

! This file is part of "Opt'n Path".

!

!  "Opt'n Path" is free software: you can redistribute it and/or modify

!  it under the terms of the GNU Affero General Public License as

!  published by the Free Software Foundation, either version 3 of the License,

!  or (at your option) any later version.

!

!  "Opt'n Path" 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 Affero General Public License for more details.

!

!  You should have received a copy of the GNU Affero General Public License

!  along with "Opt'n Path". If not, see <http://www.gnu.org/licenses/>.

!

! Contact The Office of Technology Licensing, valorisation@ens-lyon.fr,

! for commercial licensing opportunities.

!----------------------------------------------------------------------

  Use Path_module, only : pi,ncart

  IMPLICIT NONE

  INTEGER, PARAMETER :: KINT=KIND(1)

  INTEGER, PARAMETER :: KREAL=KIND(1.D0)

  INTEGER(KINT), INTENT(IN) :: Nat,NCoord

  CHARACTER(32), INTENT(IN) :: Coord

  REAL(KREAL), INTENT(INOUT) :: Step(NCoord)

  REAL(KREAL), INTENT(IN) :: GeomOld(NCoord)

  ! As this subroutine is here for debugging, debug=T !

  LOGICAL, PARAMETER :: debug=.TRUE.

  ! Variables

  INTEGER(KINT) :: IBeg, Idx,Iat

  REAL(KREAL) ::  Fact

  ! Parameters

  REAL(KREAL),PARAMETER :: eps=1e-8

  INTERFACE

     function valid(string) result (isValid)

       CHARACTER(*), intent(in) :: string

       logical                  :: isValid

     END function VALID

  END INTERFACE

  if (.NOT.Valid("CheckStep")) RETURN

  if (nat.LE.2) THEN

     if (debug) WRITE(*,*) "Check-Step useless for 2 or less atoms !"

     return

  END IF

  if (debug) WRITE(*,*) "=========================== Entering Check_Step ===================="

  Fact=1.d0

  SELECT CASE(COORD)

  CASE ('ZMAT')

     Idx=3

     IF (STEP(Idx).GT.Eps) THEN

        If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

           Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

           WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

        END IF

        If (GeomOld(Idx)+Step(Idx).LE.0) THEN

           Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

           WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx

        END IF

     END IF

     If (Nat.GT.3) THEN

        Idx=5

        IF (STEP(Idx).GE.Eps) THEN

           If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

              Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

           END IF

           If (GeomOld(Idx)+Step(Idx).LE.0) THEN

              Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx

           END IF

        END IF

        DO Iat=5,Nat

           Idx=Idx+3

           IF (STEP(Idx).GE.Eps) THEN

              If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

                 Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

                 WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

              END IF

              If (GeomOld(Idx)+Step(Idx).LE.0) THEN

                 Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

                 WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx      

              END IF

           END IF

        END DO

     END IF

  CASE ('MIXED')

     SELECT CASE (NCart)

     CASE (1:2)

        Idx=3

        IF (STEP(Idx).GE.Eps) THEN

           If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

              Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

           END IF

           If (GeomOld(Idx)+Step(Idx).LE.0) THEN

              Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx

           END IF

        END IF

        IF (Nat.GT.3) THEN

           Idx=5

           IF (STEP(Idx).GE.Eps) THEN

              If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

                 Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

                 WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

              END IF

              If (GeomOld(Idx)+Step(Idx).LE.0) THEN

                 Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

                 WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx

              END IF

           END IF

        END IF

        IBeg=5

     CASE (3:)

        IBeg=NCart+1

        Idx=3*Ncart+2

     END SELECT

     DO Iat=5,Nat

        IF (STEP(Idx).GE.Eps) THEN

           If (GeomOld(Idx)+Step(Idx).GE.Pi) THEN

              Fact=min(Fact,0.999d0*(Pi-GeomOld(Idx))/Step(Idx))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle >=180. Idx=",Idx

           END IF

           If (GeomOld(Idx)+Step(Idx).LE.0) THEN

              Fact=min(Fact,abs(0.999d0*GeomOld(Idx)/Step(Idx)))

              WRITE(*,*) "WARNING: Step reduced to prevent valence angle <=0. Idx=",Idx

           END IF

        END IF

        Idx=Idx+3

     END DO

  CASE ('CART','HYBRID','BAKER')

     if (debug) WRITE(*,*) "DBG Check_step:  Check useless for COORD=",TRIM(COORD)

  CASE DEFAULT

     WRITE(*,*) "COORD=",TRIM(COORD)," Not recognized in Check_step"

     STOP

  END SELECT

  If (debug) WRITE(*,*) "Check_Step: Fact=",Fact

  Step=Step*Fact

  if (debug) WRITE(*,*) "=========================== Exiting Check_Step ===================="

END SUBROUTINE Check_step