Transition state opt

DFT

# Zikuan Wang, 2019.7.17
#
# Optfreq of the HCN -> HNC isomerization TS (Hessian is calculated numerically).
# A test of: 
#  (1) TS optimization;
#  (2) Numerical Hessian;
#  (3) Thermochemistry analysis.
#
# Initial geometry: taken from Baker's test set
#
# Benchmark:
#   Geometry optimization converged in 12 iterations
#   Energy: -93.22419570 a.u.
#   Converged geometry:
#   Molecular Cartesian Coordinates (X,Y,Z) in Angstrom : 
#      C           0.27970346,      0.48251179,      0.00000000,
#      N          -0.40437299,     -0.48933673,      0.00000000,
#      H          -0.86580909,      0.83037007,      0.00000000,
#   
#   Vibrational frequencies (cm^{-1}):
#      -1121.2902    2090.4380    2628.0176
#   Gibbs free energy correction: -6.437983 kcal/mol
#
#   ORCA 4.0.0:
#   Energy: -93.224198601087 a.u.
#   Vibrational frequencies (cm^{-1}):
#      -1122.04      2091.07      2626.81
#   Gibbs free energy correction: -6.45 kcal/mol
#   (note that ORCA's treatment of rotational number is wrong, thus the Gibbs
#   free energy correction is manually corrected)
#
# Allowed error: 1.d-3 Bohr for geometry, 1.d-5 a.u. for energy,
#                3 cm^{-1} for frequency, 0.1 kcal/mol for Gibbs free energy correction
#
$compass
title
 HCN <-> HNC transition state
basis
 def2-SVP
geometry
 C                  0.00000000    0.00000000    0.00000000
 N                  0.00000000    0.00000000    1.14838000
 H                  1.58536000    0.00000000    1.14838000
end geometry
skeleton
check
$end

$bdfopt
iprt
 3
solver
 1
hess
# Calculate initial Hessian to aid geometry convergence;
# calculate final Hessian to obtain frequencies and thermochemical data.
# If only the frequencies at the current geometry is needed (without optimization),
# replace "init+final" by "only".
 init+final
iopt
 10 # specifies a TS optimization
$end

$xuanyuan
direct
schwarz
$end

$scf
rks
dft
 b3lyp
$end

$resp
geom
$end