Q-Chem also supports the non-perturbative
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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 analyse both polarization
(POL) and charge transfer (CT) process of inter-molecular interactions.
The non-perturbative polarization and charge transfer analysis is currently not compatible with the ALMO-EDA2 jobs, and need to be invoked by REM variable GEN_SCFMAN_EDA2 = 1. Perturbative CT analysis can be invoked by setting EDA_PCT_A = 1, while non-perturbative POL and CT analysis can be invoked by setting EDA_POL_A = 1 and EDA_VCT_A = 1 respectively. The POL analysis
uses the recently developed fragment density matrix connecting method and can break the energy decrease and charge transfer of the POL process into exact fragment 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 the energy decrease 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 COVPs that contributes more than kJ/mol in energy decrease, and the default value is set to 500.
To visualize the COVPs, set
EDA_SAVE_COVP = 1, MAKE_CUBE_FILES = true and PLOTS = true to save the orbitals as cube files, which can be visualized using IQmol, VMD or other visualization softwares. The natural orbitals for chemical valence (NOCV) method can also be used by setting EDA_NOCV = 1. To select the significant NOCVs, set EDA_NOCV_THRESH = to print out NOCVs that contributes more than kJ/mol in energy decrease, and the default value is set to 500. The NOCV analysis includes the POL process, CT process, and the traditional NOCV results from FRZ state to CT state. As pointed out in this paper
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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 QChem also supports quadrature number 3 and 5.
UHF analysis will be used if at least one of the fragments has open-shell structure, it can also be forced by setting UHF=1. 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:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not use the new ALMO-EDA framework
1
Use the new ALMO-EDA framework
RECOMMENDATION:
Set to 1 to perform non-perturbative CT analysis
EDA_PCT_A
EDA_PCT_A
Perform perturbative CT analysis
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not perform perturbative CT analysis
1
Perform perturbative CT analysis
RECOMMENDATION:
Set to 1 to perform perturbative CT analysis
EDA_VCT_A
EDA_VCT_A
Perform non-perturbative CT analysis
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not perform non-perturbative CT analysis
1
Perform non-perturbative CT analysis.
RECOMMENDATION:
Set to 1 to perform non-perturbative CT analysis
EDA_POL_A
EDA_POL_A
Perform EDA for polarization process
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not perform EDA for polarization process
1
Perform EDA for polarization process
RECOMMENDATION:
Set to 1 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:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not save significant COVPs
1
Save significant COVPs
RECOMMENDATION:
Set to 1 to save COVPs. Note REMs for plotting cube files need also be set
EDA_NOCV
EDA_NOCV
Perform NOCV analysis
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0
Do not do NOCV analysis
1
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 point_group_symmetry False integral_symmetry false 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 $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 point_group_symmetry False integral_symmetry false 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 $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 point_group_symmetry False integral_symmetry false 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 $end $plots grid_points 100 100 100 $end
The non-perturbative POL and CT analysis methods have also been implemented in EDA2 driver so that features available in EDA2 can be used, such as energy decomposition with external point charges and using different SCF algorithms. 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.
$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 scf_print_frgm true point_group_symmetry False integral_symmetry false basis 6-31g* scf_algorithm gdm thresh 12 incfock false mem_total 16000 scf_convergence 7 eda_pol_a 1 eda_vct_a 1 eda_covp_thresh 500 eda_save_covp 0 eda_nocv 1 eda_save_nocv 0 eda_nocv_thresh 500 eda_nocv_quadrature 1 make_cube_files true plots true $end $plots grid_points 50 50 50 $end