6
2 Actual Potentials of Theoretical Chemistry: What Can Be Obtained
E
R (Nuclear Coordinates)
Fig. 2.3 Simple illustration of several local minimum points on the PES. The true minimum point
is indicated by a solid circle
would be particularly effective when one has to deal with complicated molecular
system requiring conformation analysis of oligomers or “supermolecules” consisting
of large number of molecules. For comparatively small supermolecules it is possible
to be treated by the optimization process of the ordinary molecules.
An example of the structure-optimized supermolecule in which several H 2
molecules are adsorbed onto an organometallic complex (Ca-catecholate) is shown
in Fig. 2.4a. This structure has been obtained by theoretical calculation employing
DFT/ωB97M-V/def2-TZVPD scheme that can handle molecular system or supermolecule including long-range interactions such as the van der Waals one (Tsivion
et al. 2017). The notation for the calculations A/B/C signifies “calculation
method/detailed scheme/basis set” throughout this book, where B (detailed scheme)
is included upon necessity. This adsorption is probably caused by van der Waals
(a)
(b)
Fig. 2.4 Optimized structures of a calcium catecholate with four H 2 molecules adsorbed and
b formic-acid dimer including a water molecule. Red and blue balls show oxygen and related
hydrogen atoms, respectively, and black-gray one in the pentagon of a calcium. In b thin red lines
represent hydrogen bonds with the distances in Å. From Tsivion et al. (2017) Copyright © 2017
by John Wiley & Sons, Inc. Reprinted by permission of John Wiley & Sons, Inc. Reprinted from
Krishnakumar and Maity (2017), Copyright 2017, with permission from Elsevier
2 Actual Potentials of Theoretical Chemistry: What Can Be Obtained
E
R (Nuclear Coordinates)
Fig. 2.3 Simple illustration of several local minimum points on the PES. The true minimum point
is indicated by a solid circle
would be particularly effective when one has to deal with complicated molecular
system requiring conformation analysis of oligomers or “supermolecules” consisting
of large number of molecules. For comparatively small supermolecules it is possible
to be treated by the optimization process of the ordinary molecules.
An example of the structure-optimized supermolecule in which several H 2
molecules are adsorbed onto an organometallic complex (Ca-catecholate) is shown
in Fig. 2.4a. This structure has been obtained by theoretical calculation employing
DFT/ωB97M-V/def2-TZVPD scheme that can handle molecular system or supermolecule including long-range interactions such as the van der Waals one (Tsivion
et al. 2017). The notation for the calculations A/B/C signifies “calculation
method/detailed scheme/basis set” throughout this book, where B (detailed scheme)
is included upon necessity. This adsorption is probably caused by van der Waals
(a)
(b)
Fig. 2.4 Optimized structures of a calcium catecholate with four H 2 molecules adsorbed and
b formic-acid dimer including a water molecule. Red and blue balls show oxygen and related
hydrogen atoms, respectively, and black-gray one in the pentagon of a calcium. In b thin red lines
represent hydrogen bonds with the distances in Å. From Tsivion et al. (2017) Copyright © 2017
by John Wiley & Sons, Inc. Reprinted by permission of John Wiley & Sons, Inc. Reprinted from
Krishnakumar and Maity (2017), Copyright 2017, with permission from Elsevier