# Example: Relativistic ZORA TS search: CH4 + HgCl2 <==> CH3HgCl + HCl¶

Download TS_CH4_HgCl2.run

A ZORA scalar relativistic Transition State calculation.

\$ADFBIN/adf << eor
TITLE  Transition State: CH4 + HgCl2 <==> CH3HgCl + HCl

noprint sfo,frag
print atdist

GEOMETRY
TransitionState
END
TSRC
DIST 1 5 1.0
END

Relativistic scalar ZORA

Basis
Type TZP
Core small
Cl TZP/Cl.2p
End

ATOMS
C         0.049484    0.042994    0.000000
H        -0.068980    0.638928   -0.915972
H        -0.068980    0.638928    0.915972
H        -0.841513   -0.626342    0.000000
H         0.555494   -1.148227    0.000000
Hg        2.303289   -0.007233    0.000000
Cl        4.429752    0.776056    0.000000
Cl        1.342057   -2.676083    0.000000
END

endinput
eor


For the density-functional the Local Density approximation is used (no GGA corrections).

At each geometry cycle the interatomic distance matrix is printed (print atdist).

The initial geometry is a reasonable but not very accurate estimate of the Transition State. The program needs quite a few cycles to converge, which is rather typical for TS searches: they are a lot more tricky and fail more often than a simple minimization. The TSRC key is used to specify a reaction coordinate along which the transition state is sought for. This feature is especially useful when an accurate Hessian is not available.