T.V. — A transition vector is provided for IRC or PATH.
T.V.
T.V.=n
The oriented transition vector at the starting point of a PATH (internal coordinates) or IRC (Cartesian coordinates) calculation will be specified in the data file. T.V. data should be entered in an extra input data section in the same order as the optimized coordinates, in free format (data separated by a space, a comma or a semicolon, up to 80 characters per line). This data section is located after the geometry section and is initiated by the string
$$ t.v. - transition vector coordinates
which can be abbreviated as
$$ t.v.
as in the following example:
$$ t.v. -0.1790 0.2050 -0.4960 0.2050 -0.4960 -0.1740 -0.0165 0.1160 0.1010 -0.0166 0.1160 0.1000 -0.0083 -0.0021 -0.1230 -0.0084 0.0021 -0.1230 0.0020 -0.0567 -0.3710 0.0200 -0.0567 -0.3710 $$ end of extra data
n
This option causes a transition vector to be automatically calculated at the starting
point of a PATH or
IRC calculation. Unlike T.V.,
T.V.=n
acts as a multi-step job:
The geometry is optimized by LTRD
The transition vector is taken as the n^{th} eigenvector of the mass-weighted Cartesian Hessian matrix.
Follow IRC/PATH in the direction of the transition vector.
Follow IRC/PATH in the reverse direction of the transition vector.
A negative value of n will produce the same IRC/PATH except that the path is traced in the opposite order (i.e. it is reversed). T.V.=0 is not allowed.
For examples of the use of the T.V. keyword, see Chapter 29, Intrinsic Reaction Coordinate (IRC) Calculation and Chapter 28, PATH Calculation with Transition Vector.
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