Q-Chem also supports the non-perturbative
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(2021),
23,
pp. 928.
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(variational) energy and
charge decomposition analysis in the second-generation ALMO-EDA framework. The advantage
of this method over the perturbative CT analysis method is that the energy and charge
decompositions are both exact and there are no higher-order terms left. Currently, this method is
implemented for both restricted and unrestricted SCF calculations, and is eligible to analyze both
polarization
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J. Chem. Theory Comput.
(2023),
19,
pp. 8624.
Link
(POL) and charge transfer (CT) processes of intermolecular interactions.
The non-perturbative polarization and charge transfer analysis can be performed using the GEN_SCFMAN_EDA2
driver (GEN_SCFMAN_EDA2 = TRUE). Perturbative CT analysis can be invoked by setting
EDA_PCT_A = TRUE, while non-perturbative POL and CT analysis can be invoked by setting
EDA_POL_A = TRUE and EDA_VCT_A = TRUE, respectively. The POL analysis
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(2023),
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pp. 8624.
Link
uses the recently developed fragment density matrix connecting method and can break the energy
lowering and charge shift in the POL process into exactly fragment-wise additive sums. The CT analysis will print out the
pairwise energy and charge changes between fragments as matrices, with fragment labels starting from 0, and the
interpretation is that the energy lowering and charge transfer happens due to electron donation from the fragments labeled
in the rows to the fragments labeled in the columns.
The default orbital analysis method is the complementary occupied-virtual pairs (COVP) method. To select the significant COVPs,
set EDA_COVP_THRESH = to print out the COVPs that contributes more than kJ/mol to the energy
decrease, and the default value is set to 500. To visualize the COVPs, set EDA_SAVE_COVP = TRUE,
MAKE_CUBE_FILES = TRUE and PLOTS = TRUE to save the orbitals as cube files, which can
be visualized using IQmol, VMD, or other visualization software. The natural orbitals for chemical valence (NOCV) analysis can also be
performed by setting EDA_NOCV = TRUE. To select the significant NOCVs, set EDA_NOCV_THRESH =
to print out NOCVs that contributes more than kJ/mol to energy decrease, and the default value is also set to 500.
The NOCV analysis includes the POL process, CT process, and the traditional NOCV results which combine the POL and CT processes.
As pointed out in this paper
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pp. 7428.
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, the ETS-NOCV method approximates the effective Fock matrix integration with only one quadrature,
which is set by EDA_NOCV_QUADRATURE =1, and Q-Chem also supports quadrature number 3 and 5.
Unrestricted analysis will be used if at least one of the fragments has an open-shell structure. It can also be forced by setting UNRESTRICTED=TRUE. One caveat is that the current implementation does not support the OCC_RI_K algorithm, and the calculation will crash if this REM is set true.
GEN_SCFMAN_EDA2
GEN_SCFMAN_EDA2
Perform ALMO-EDA calculations using the GEN_SCFMAN_EDA2 driver (differing from jobs with EDA2 0)
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not use the new ALMO-EDA framework
TRUE
Use the new ALMO-EDA framework
RECOMMENDATION:
Set to TRUE to perform non-perturbative CT analysis using this driver
EDA_PCT_A
EDA_PCT_A
Perform perturbative CT analysis
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not perform perturbative CT analysis
TRUE
Perform perturbative CT analysis
RECOMMENDATION:
Set to TRUE to perform perturbative CT analysis
EDA_VCT_A
EDA_VCT_A
Perform non-perturbative CT analysis
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not perform non-perturbative CT analysis
TRUE
Perform non-perturbative CT analysis.
RECOMMENDATION:
Set to TRUE to perform non-perturbative CT analysis
EDA_POL_A
EDA_POL_A
Perform EDA for polarization process
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not perform EDA for polarization process
TRUE
Perform EDA for polarization process
RECOMMENDATION:
Set to TRUE to perform EDA for polarization process
EDA_COVP_THRESH
EDA_COVP_THRESH
Specifies the significance above which the COVPs will be saved
TYPE:
INTEGER
DEFAULT:
500
OPTIONS:
COVPs that contributes more than kJ/mol in energy decrease will be saved
RECOMMENDATION:
None
EDA_SAVE_COVP
EDA_SAVE_COVP
Save significant COVPs or not
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not save significant COVPs
TRUE
Save significant COVPs
RECOMMENDATION:
Set to TRUE to save COVPs. Note that REMs for plotting cube files need also be set
EDA_NOCV
EDA_NOCV
Perform NOCV analysis
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not do NOCV analysis
TRUE
Do NOCV analysis
RECOMMENDATION:
None
EDA_NOCV_THRESH
EDA_NOCV_THRESH
Specifies the significance above which the NOCVs will be saved
TYPE:
INTEGER
DEFAULT:
500
OPTIONS:
NOCVs that contributes more than kJ/mol in energy decrease will be saved
RECOMMENDATION:
None
EDA_SAVE_NOCV
EDA_SAVE_NOCV
Save significant COVPs or not
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not save significant NOCVs
1
Save significant NOCVs
RECOMMENDATION:
Set to 1 to save NOCVs. Note REMs for plotting cube files need also be set
EDA_NOCV_QUADRATURE
EDA_NOCV_QUADRATURE
Number of quadratures used to integrate effective fock matrix
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
1
Use 1 quadrature
3
Use 3 quadratures
5
Use 5 quadratures
RECOMMENDATION:
Most of the time, one quadrature is enough. However, in cases where the NOCV energy decreases are very different from the corresponding COVP results, it is recommended to increase the quadrature numbers.
Example 12.20 Restricted EDA calculation for the HO-Na system with non-perturbative POL and CT analysis.
$molecule 1 1 -- 0 1 H -0.73946 0.94887 0.78379 O -1.16910 0.63297 -0.02844 H -2.12156 0.70793 0.14730 -- 1 1 Na -0.17266 -0.04338 -1.86190 $end $comment EDA2 (R) calculation with variational POL and CT analyses based on the gen_scfman_eda2 driver $end $rem method B3LYP scf_print_frgm 1 gen_scfman_final 1 scf_print_frgm 1 basis 6-31G* scf_algorithm diis thresh 12 incfock false mem_total 16000 scf_convergence 7 scf_final_print 2 child_mp 1 child_mp_orders 232 ! nDQ gen_scfman_eda2 1 eda_pol_a 1 eda_pct_a 0 eda_vct_a 1 eda_covp_thresh 500 eda_save_covp 0 make_cube_files true plots true point_group_symmetry false integral_symmetry false $end $plots grid_points 50 50 50 $end
Example 12.21 Unrestricted EDA calculation for the CH-Na system with non-perturbative POL and CT analysis.
$molecule 1 2 -- 0 2 C¯-1.447596 -0.000023 0.000019 H¯-1.562749 0.330361 -1.023835 H¯-1.561982 0.721445 0.798205 H¯-1.561187 -1.052067 0.225866 -- 1 1 Na¯ 1.215591 0.000036 -0.000032 $end $comment EDA2 (U) calculation with variational POL and CT analyses based on the gen_scfman_eda2 driver $end $rem method B3LYP scf_print_frgm true basis aug-cc-PVTZ scf_algorithm diis thresh 12 incfock false mem_total 16000 scf_convergence 7 child_mp 1 child_mp_orders 232 ! nDQ gen_scfman_eda2 1 eda_pol_a 1 eda_pct_a 0 eda_vct_a 1 eda_covp_thresh 500 eda_save_covp 0 make_cube_files true plots true point_group_symmetry false integral_symmetry false $end $plots grid_points 50 50 50 $end
Example 12.22 Unrestricted EDA calculation for the Rn-CH system with non-perturbative POL and CT analysis and NOCV analysis
$molecule 1 2 -- 0 1 C 0.0551597051 0.0364080371 -0.0375528310 H -0.0563410694 -1.0144740143 -0.3153331540 H -0.0537558345 0.7868509829 -0.8318467516 H -0.8718690962 0.2438110339 0.5677588397 H 1.0408273042 0.1810559688 0.4109829953 -- 1 2 Rn -0.2646060092 0.6373989916 3.0026329017 $end $rem method b3lyp gen_scfman_final 1 scf_print_frgm 1 basis def2-tzvp ecp def2-ecp scf_algorithm diis thresh 12 incfock 0 mem_total 16000 scf_final_print 2 iprint 20000000 scf_convergence 7 child_mp 1 child_mp_orders 232 ! nDQ gen_scfman_eda2 1 eda_pol_a 1 eda_pct_a 0 eda_vct_a 1 eda_save_covp 0 eda_nocv 1 eda_save_nocv 0 eda_covp_thresh 500 eda_nocv_thresh 500 eda_nocv_quadrature 1 make_cube_files true plots true point_group_symmetry false integral_symmetry false $end $plots grid_points 100 100 100 $end
In Q-Chem 6.1 and after, the non-perturbative POL and CT analysis methods are enabled in EDA2 driver so that features available in EDA2 can be used, such as frozen energy decomposition, inclusion of solvation models, etc. A sample input file is shown below.
Example 12.23 Unrestricted EDA calculation for the CH-Na system with non-perturbative POL and CT analysis using the EDA2 driver. The significant COVPs will be plotted.
$molecule 1 2 -- 0 2 C -1.447596 -0.000023 0.000019 H -1.562749 0.330361 -1.023835 H -1.561982 0.721445 0.798205 H -1.561187 -1.052067 0.225866 -- 1 1 Na 1.215591 0.000036 -0.000032 $end $comment EDA2 (U) calculation with variational POL and CT analyses based on the eda2 driver $end $rem jobtype eda eda2 1 method B3LYP point_group_symmetry false basis 6-31g* scf_algorithm gdm thresh 12 eda_pol_a true eda_vct_a true eda_covp_thresh 500 eda_save_covp true eda_nocv true eda_save_nocv false eda_nocv_thresh 500 eda_nocv_quadrature 1 make_cube_files true plots true $end $plots grid_points 50 50 50 $end