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AOMix-S
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Interaction diagram for HC-CH

AOMix-FO is a part of the AOMix package. It

  • generates a wave function of a multi-fragment molecular system from the fragment wave functions (refer to APPENDIX II of the AOMix manual for details);
  • performs the analysis of MO compositions in terms of fragment molecular orbitals (FOs). The number of fragments can be from 1 (in this case, the analysis is performed relative to a user-defined, reference electronic state, see for example [PDF]) up to 4000. The program is able to treat all spin-coupling cases:
    • ferromagnetic coupling (alpha-spin FOs of Fragment X couple with alpha-spin FOs of Fragment Y, beta-spin FOs of Fragment X couple with beta-spin FOs of Fragment Y)
    • anti-ferromagnetic coupling (alpha-spin FOs of Fragment X couple with beta-spin FOs of Fragment Y, beta-spin FOs of Fragment X couple with alpha-spin FOs of Fragment Y)
    • any possible combination of ferromagnetic and anti-ferromagnetic for a case of multiple fragments;
  • calculates the amount of electron donation between fragments (the charge decomposition analysis, CDA),
  • calculates fragment orbital populations in a molecule,
  • calculates atomic orbital populations in a molecule, in non-interacting fragments (or a reference molecule if the number of fragments is 1) and the difference in AO populations,
  • prints the LCFO-MO coefficient matrix and the FO overlap matrix,
  • can be used for energy decomposition analysis (EDA, Morokuma-Ziegler), for Gaussian 98/03/09 calculations; and
  • generates the plot data for orbital interaction diagrams (see the examples below).


Electron donation and polarization

With AOMix-FO, you can analyze the electronic structure and bonding in molecules in great detail, calculate charge transfer (CT) and electronic polarization (PL) contributions, evaluate the sigma- and pi- bonding interactions, etc. [PDF file]

Here is an example of the AOMix-FO output:

  1. AOMix-FO.txt
  2. AOMix-MO-FO-alpha.txt
It is the charge decomposition analysis of the BH3CO molecule (fragment 1 is BH3 and fragment 2 is CO, HyperChem AM1 calculations). According to the analysis, the charge donation from CO to BH3 is 0.417 electrons and the back-donation from BH3 to CO is 0.143 electrons).

AOMix-FO also sets up data files for plotting the MO interaction diagrams, see Figures below.

Interaction diagram for BH3CO

Similar donation/back-donation charges (0.47 and 0.18 electrons respectively) are obtained from Gaussian 03 calculations at the HF/6-31G* level:

  1. AOMix-FO.txt
  2. AOMix-MO-FO-alpha.txt
Interaction diagram for BH3CO

Advantanges of the FO analysis:

  1. AOMix-FO can handle more than two molecular fragments (up to 99 fragments). This allows the analysis of more complex molecular systems (such as bridged metal complexes L1-M1-bridge-M2-L2, for example) than just simple binary donor-acceptor complexes;
  2. AOMix-FO can be used for spin-restricted, spin-unrestricted, and "mixed" (spin-restricted and spin-unrestricted) calculations.

Here is an example of the AOMix-FO calculation with 3 fragments where the whole molecule and the 1st fragment are treated at the spin-unrestricted DFT level (open-shell species), and the 2nd and 3rd fragments are treated at the spin-restricted DFT level (closed-shell species):

  1. AOMix-FO.txt
  2. AOMix-MO-FO-a.txt
  3. AOMix-MO-FO-b.txt

Orbital Interaction diagram for the copper-thiolate complex

The orbital interaction diagram (using Gaussian 03 and AOMix-FO at the B3LYP/TZVP level) of the Cu(HB(3,5-iPr2pz)3) and thiolate SC6F5 fragments forming the [Cu(HB(3,5-iPr2pz)3)(SC6F5)] complex. p (a2 symmetry) orbitals are shown in blue color and s orbitals (a1 symmetry) are in red.

For more details, check the following publications:

Spectroscopic and DFT Investigation of [M(HB(3,5-iPr2pz)3)(SC6F5)], (M = Mn, Fe, Co, Ni, Cu and Zn) Model Complexes: Periodic Trends in Metal-Thiolate Bonding.
S. I. Gorelsky, L. Basumallick, J. Vura-Weis, R. Sarangi, B. Hedman, K. O. Hodgson, K. Fujisawa, E. I. Solomon
Inorg. Chem., 2005, 44, 4947-4960 [PDF].

Metal-thiolate bonds in bioinorganic chemistry
E. I. Solomon, S. I. Gorelsky, A. Dey
J. Comput. Chem., 2006, 27, 1415-1428 [PDF].


Orbital Interaction diagram for the Ru-BQDI complex

The orbital interaction diagram (computed using Gaussian 03 and AOMix-FO at the B3LYP/LanL2DZ level) of the Ru(NH3)2Cl2 and BQDI fragments forming the [Ru(NH3)2Cl2(BQDI)] complex.

In this complex, the BQDI-to-Ru donation is produced by the interactions involving fragment orbitals of a1 and b2 symmetries, namely, HOFO-1 and HOFO-2 of the bqdi ligand and the LUFO and LUFO+1 of the Ru fragment (see the above figure, black and red lines). The Ru-to-BQDI back-donation is produced by the orbital interaction between the HOFO of the Ru fragment and the LUFO of the BQDI ligand of b1 symmetry. The ECDA analysis shows that the LUMO of the the complex is an anti-bonding combination of 62 % LUFO(bqdi) and 33 % HOFO(Ru). The corresponding bonding orbital (HOMO-1 of the complex) is formed by 61% HOFO(Ru) and 29% LUFO(bqdi). These orbital contributions indicate the strong back-bonding interaction and account for a transfer of ~0.7 e- from the Ru fragment to the BQDI ligand. [PDF].


Here is another example of the AOMix-FO output: the orbital interaction diagram (computed using Gaussian 03 at the B3LYP/TZVP level) of two methylidyne (CH) radicals (in the quartet spin state, S=4) forming the a linear acetelene molecule HCCH (alpha-spin orbitals are shown in blue, beta-spin orbitals are shown in red color):

Orbital Interaction diagram for HCCH

The examples of Gaussian, GAMESS, HyperChem 5.0, Spartan 08 and Q-Chem 3.2 input files for AOMix-FO and the corresponding AOMix-FO output files can be downloaded by users at this link.

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Last updated: September 2014