anchor.diff:  
       IF(ATOM .EQ. "ATOM") THEN
   
  -        ! Locate atom in a grid square along each axis on at a time
  +        ! Locate atom in a grid square along each axis one at a time
   
           DO NX = 1, MX
               XB1 = XMI + BOX*(NX-1)
               XB2 = XMI + BOX*NX
  -            IF (X(1) .GT. XB1 .AND. X(1) .LT. XB2) THEN
  +            IF (X(1) .GE. XB1 .AND. X(1) .LT. XB2) THEN
                  NXX = NX
                  EXIT
               ENDIF
  
positive.code:         DO NY = 1, MY
              YB1 = YMI + BOX*(NY-1)
              YB2 = YMI + BOX*NY
              IF (X(2) .GT. YB1 .AND. X(2) .LT. YB2) THEN
                 NYY = NY
                 EXIT
              ENDIF
  
negative.code:         DO NZ = 1, MZ
              ZB1 = ZMI + BOX*(NZ-1)
              ZB2 = ZMI + BOX*NZ
              IF (X(3) .GE. ZB1 .AND. X(3) .LT. ZB2) THEN
                 NZZ = NZ
                 EXIT
              ENDIF
  