Hi!
I am running the following code to test the optimization of a transition state followed by frequency calculations and IRC test:
molecule ts {
0 1
O 9.978538 -7.065826 -5.560229
O 9.253519 -7.435897 -4.707331
H 11.121586 -7.116893 -5.275842
H 9.800901 -7.736312 -3.707248
}
set {
basis Def2-SVP
reference rhf # To ensure that the scf guess is right
g_convergence gau # Sets the SCF convergence as scf=tight in G16
dft_spherical_points 302 # The two following options makes the grid as 'finegrid' in Gaussian
dft_radial_points 75
dft_pruning_scheme robust # Generally safe and will speed things up
opt_type ts # Options min, ts, irc
geom_maxiter 100
}
# First we optimize the TS
e, wfn = optimize('M06-2X-D3ZERO2B', return_wfn=True)
wfn.to_file('OPT')
ts.save_xyz_file('HOOH_ts_opt.xyz',1)
# Clone the final geometries for the IRC calculations
irc_forwards = ts.clone()
irc_backwards = ts.clone()
# Now we get the frequencies
e, wfn_freq = frequency('M06-2X-D3ZERO2B', ref_gradient=wfn.gradient(), return_wfn=True) # Save the frequency caluclation in the wavefunction for printing
# Now we move to the IRC caluclations
set {
basis Def2-SVP
reference rhf # To ensure that the scf guess is right
g_convergence gau # Sets the SCF convergence as scf=tight in G16
dft_spherical_points 302 # The two following options makes the grid as 'finegrid' in Gaussian
dft_radial_points 75
dft_pruning_scheme robust # Generally safe and will speed things up
opt_type irc # Options min, ts, irc
geom_maxiter 100
}
# IRC forward ####################################
set {
irc_step_size 0.25
irc_points 20
irc_direction forward
cart_hess_read = True
full_hess_every = -1
}
e, irc_forw = optimize('M06-2X-D3ZERO2B', molecule=irc_forwards, ref_gradient=wfn_freq.gradient())
irc_forwards.save_xyz_file('ircf.xyz',1)
# IRC backward ####################################
set {
irc_step_size 0.25
irc_points 20
irc_direction backward
cart_hess_read = True
full_hess_every = -1
}
e, irc_back = optimize('M06-2X-D3ZERO2B', molecule=irc_backwards, ref_gradient=wfn_freq.gradient())
irc_backwards.save_xyz_file('ircr.xyz',1)
Everything goes well for the optimization of the TS and the calculations of the frequencies.
My issues are two:
-
If I add the “wfn_freq.to_file(‘wfn_freq’)” command after the frequency calculation (not shown in the code above), I get the same error I reported in a previous post here.
-
If I skip that step and try to proceed directly with the IRC calculation as shown in the code above, I get the following error:
Printing out the relevant lines from the Psithon --> Python processed input file:
core.set_global_option("IRC_STEP_SIZE", 0.25)
core.set_global_option("IRC_POINTS", 20)
core.set_global_option("IRC_DIRECTION", "forward")
core.set_global_option("CART_HESS_READ", "True")
core.set_global_option("FULL_HESS_EVERY", -1)
--> e, irc_forw = optimize('M06-2X-D3ZERO2B', molecule=irc_forwards, ref_gradient=wfn_freq.gradient())
irc_forwards.save_xyz_file('ircf.xyz',1)
core.set_global_option("IRC_STEP_SIZE", 0.25)
core.set_global_option("IRC_POINTS", 20)
core.set_global_option("IRC_DIRECTION", "backward")
core.set_global_option("CART_HESS_READ", "True")
!-----------------------------------------------------------------------!
! !
! [Errno 2] No such file or directory: 'HOOH_freq_irc.ts.1706054.hess' !
! !
!-----------------------------------------------------------------------!