Studying the numerical stability of the initial guess density in OO-DFT
methods
144
Phys. Chem. Chem. Phys.
(2025),
27,
pp. 17533.
Link
, we concluded that, in the case of CT excitations,
a suitable guess density can be obtained for a fragmented system by using
the absolutely localized molecular orbitals (ALMO)
method
1314
Theor. Chem. Acc.
(1980),
57,
pp. 169.
Link
,
440
Int. J. Quantum Chem.
(1996),
60,
pp. 157.
Link
.
The ALMO method is presented in Section 12.5.
In this method, the atom-centered Gaussian basis is localized, and ionized
fragments can be computed.
The resulting density is properly polarized for the calculation of intermolecular
CT excitations, and can be further relaxed using the SGM method.
Convergence is robust, and the input preparation is more straightforward compared
to the FRZ-SGM method, although it is not straightforwardly transferable to
covalently bonded systems.
Example 7.7.57 Example input for the calculation of the lowest-lying intermolecular charge
transfer excitation energy in the anthracene-tetracyanoethylene dimer using
ALMO-SGM
144
Phys. Chem. Chem. Phys.
(2025),
27,
pp. 17533.
Link
and the nonequilibrium conductor-like polarizable
continuum (C-PCM) solvation model
1530
J. Chem. Phys.
(2015),
143,
pp. 204104.
Link
,
940
J. Phys. Chem. A
(2015),
119,
pp. 5446.
Link
for dichloromethane (DCM).
The excitation energy and transition dipole moment to the CT excitation are
calculated.
$molecule 0 1 --- 0 1 C 0.0000024972 -1.3939649880 -1.2808767121 C 0.0000025051 1.3939644651 -1.2808767282 C -1.2186821591 -0.7141902026 -1.3071478062 C 1.2186864041 -0.7141896146 -1.3071387589 C -1.2186821243 0.7141897115 -1.3071478120 C 1.2186863774 0.7141891121 -1.3071387637 C -2.4644125118 -1.4013703998 -1.3157095813 C 2.4644171860 -1.4013692038 -1.3157202646 C -2.4644123040 1.4013701670 -1.3157095358 C 2.4644169957 1.4013689421 -1.3157202095 C -3.6355756821 -0.7091886883 -1.3209438667 C 3.6355802205 -0.7091872626 -1.3209819362 C -3.6355756149 0.7091887273 -1.3209437866 C 3.6355801612 0.7091872572 -1.3209818529 H 0.0000024198 -2.4788109280 -1.2699497414 H 0.0000024299 2.4788104048 -1.2699497864 H -2.4609901895 -2.4845736396 -1.3142370557 H 2.4609967495 -2.4845724379 -1.3142287226 H -2.4609894842 2.4845734123 -1.3142370884 H 2.4609960822 2.4845721821 -1.3142287476 H -4.5790700028 -1.2397330066 -1.3238607200 H 4.5790785788 -1.2397242939 -1.3239159625 H -4.5790698620 1.2397331701 -1.3238605613 H 4.5790784507 1.2397244044 -1.3239157964 --- 0 1 C -0.0000060964 -0.6804948447 1.8114150650 C -0.0000061169 0.6804936064 1.8114151444 C 1.2158428238 -1.4225502703 1.8615716187 C -1.2158551579 -1.4225518647 1.8615295498 C 1.2158426874 1.4225492361 1.8615717275 C -1.2158551065 1.4225507587 1.8615296588 N 2.1947618514 -2.0185775621 1.9228707722 N -2.1947808705 -2.0185720940 1.9227856078 N 2.1947616310 2.0185766696 1.9228709110 N -2.1947807686 2.0185710748 1.9227857419 $end $comment ALMO on the ground state to set up the localized basis $end $rem jobtype sp scf_guess fragmo FRGM_METHOD STOLL SCF_PRINT_FRGM TRUE method wB97xD basis def2-TZVP scf_max_cycles 1000 sym_ignore true symmetry false thresh 14 unrestricted true solvent_method pcm $end $rem_frgm unrestricted true SCF_CONVERGENCE 5 SCF_ALGORITHM DIIS_GDM THRESH 14 $end $pcm theory iefpcm $end $solvent Dielectric 8.9 Dielectric_Infi 2.03 $end @@@ $rem unrestricted true jobtype sp method wB97xD scf_guess read basis def2-TZVP scf_algorithm diis_gdm max_scf_cycles 250 sym_ignore true symmetry false IQMOL_FCHK TRUE trans_mom_save true solvent_method pcm $end $pcm theory iefpcm rf_ptss_save true $end $solvent Dielectric 8.9 Dielectric_Infi 2.03 $end $molecule read $end @@@ $molecule 0 1 --- 1 2 C 0.0000024972 -1.3939649880 -1.2808767121 C 0.0000025051 1.3939644651 -1.2808767282 C -1.2186821591 -0.7141902026 -1.3071478062 C 1.2186864041 -0.7141896146 -1.3071387589 C -1.2186821243 0.7141897115 -1.3071478120 C 1.2186863774 0.7141891121 -1.3071387637 C -2.4644125118 -1.4013703998 -1.3157095813 C 2.4644171860 -1.4013692038 -1.3157202646 C -2.4644123040 1.4013701670 -1.3157095358 C 2.4644169957 1.4013689421 -1.3157202095 C -3.6355756821 -0.7091886883 -1.3209438667 C 3.6355802205 -0.7091872626 -1.3209819362 C -3.6355756149 0.7091887273 -1.3209437866 C 3.6355801612 0.7091872572 -1.3209818529 H 0.0000024198 -2.4788109280 -1.2699497414 H 0.0000024299 2.4788104048 -1.2699497864 H -2.4609901895 -2.4845736396 -1.3142370557 H 2.4609967495 -2.4845724379 -1.3142287226 H -2.4609894842 2.4845734123 -1.3142370884 H 2.4609960822 2.4845721821 -1.3142287476 H -4.5790700028 -1.2397330066 -1.3238607200 H 4.5790785788 -1.2397242939 -1.3239159625 H -4.5790698620 1.2397331701 -1.3238605613 H 4.5790784507 1.2397244044 -1.3239157964 --- -1 -2 C -0.0000060964 -0.6804948447 1.8114150650 C -0.0000061169 0.6804936064 1.8114151444 C 1.2158428238 -1.4225502703 1.8615716187 C -1.2158551579 -1.4225518647 1.8615295498 C 1.2158426874 1.4225492361 1.8615717275 C -1.2158551065 1.4225507587 1.8615296588 N 2.1947618514 -2.0185775621 1.9228707722 N -2.1947808705 -2.0185720940 1.9227856078 N 2.1947616310 2.0185766696 1.9228709110 N -2.1947807686 2.0185710748 1.9227857419 $end $comment ALMO should provide a good guess for SGM $end $rem jobtype sp scf_guess fragmo FRGM_METHOD STOLL SCF_PRINT_FRGM TRUE method wB97xD basis def2-TZVP scf_max_cycles 1000 sym_ignore true symmetry false thresh 14 unrestricted true solvent_method pcm $end $rem_frgm unrestricted true SCF_CONVERGENCE 5 SCF_ALGORITHM DIIS_GDM THRESH 14 $end $pcm theory iefpcm $end $solvent Dielectric 8.9 Dielectric_Infi 2.03 $end @@@ $rem unrestricted true thresh 14 scf_convergence 5 scf_algorithm sgm_ls method wB97xD basis def2-TZVP scf_guess read scf_max_cycles 500 sym_ignore true symmetry false MAKE_CUBE_FILES TRUE PLOTS TRUE IQMOL_FCHK TRUE trans_mom_read true solvent_method pcm $end $pcm theory iefpcm rf_ptss_read true $end $solvent Dielectric 8.9 Dielectric_Infi 2.03 $end $plots total_density 0 grid_spacing 0.05 $end $molecule read $end