# Example: (non-)Linear Transit: H2O¶

Download Transit_H2O.run

#! /bin/sh

# ADF is capable of performing both linear transits, and non-linear transits,
# and is the default when the LINEARTRANSIT or TRANSIT sub-block is included in
# the 'Geometry' block.

# The new transit code works differently to the old: the transit is represented
# as a sequence of constrained optimizations. A 'Constraints' block is used to
# delineate the constraints applied at each stage of the transit.

# Non-linear transits are possible, and can even be combined with linear
# transits in other coordinates. To perform a non-linear transit in a particular
# coordinate, explicit values must be given.

Title WATER Transit (non-linear), with the new optimizer branch

Atoms
O             0.000000     0.000000     0.000000
H             0.000000    -0.689440    -0.578509
H             0.000000     0.689440    -0.578509
End

Symmetry NOSYM

Constraints
dist 1 2 0.8 1.0 1.25 1.5
angle 2 1 3 start=100.0 end=120.0
End

Basis
Type SZ
Core Large
End

Geometry
LinearTransit 4
Optim Deloc
!  Constraints PartialConverge
End

eor

# In the example above, 4 values are given for the distance between atoms 1 and
# 2. This distance constraint will be applied simultaneously with the linear
# transit constraints for the angle, with other degrees of freedom optimized at
# each stage of the transit.

# Finally, it should be pointed out that 'full constraints' are used by
# default in the transit calculations. These constraints are required to be
# fully met at each intermediate geometry. You can use partially converged constraints,
# that are fully met only at the converged geometries, by supplying the
# PARTIALCONVERGE option to the 'Constraints' subkey of the 'Geometry' block (not
# to be confused with the 'Constraints' block at root level).