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19.11 Total Position-Spread tensor (TPS)

Bibliography:

M. El Khatib, T. Leininger, G.L. Bendazzoli, and S. Evangelisti, Chem. Phys. Lett. 591, 58 (2014).

O. Brea, M. El Khatib, C. Angeli, G.L. Bendazzoli, S. Evangelisti, and T. Leininger, J. Chem. Theory Comput. 9, 5286 (2013).

All publications resulting from use of this program must acknowledge the above. See also:

W. Kohn, Phys. Rev. 133 (1964) A171.
R. Resta, S. Sorella, Phys. Rev. Lett. 82 (1999) 370.

The total position-spread (TPS) tensor is a quantity originally introduced in the modern theory of electrical conductivity. In the case of molecular systems, this tensor measures the fluctuation of the electrons around their mean positions, which corresponds to the delocalization of the electronic charge within a molecular system. The TPS can discriminate between metals and insulators taking information from the ground state wave function. This quantity can be very useful as an indicator to characterize Intervalence charge transfer processes, the bond nature of molecules (covalent, ionic or weakly bonded), and Metal–insulator transition.

The program is invoked by TRAN2 inside the MULTI input block:

TRAN2,RXX,RYY,RZZ,RXY,RXZ,RYZ;

The three different classes of contributions to the CASSCF wave function can be printed by using the keyword:

IPRINT,TPS1;

This will print the core-core, core-active, and active-active contributions of the TPS tensor are printed.



Next: 19.12 Hints and strategies Up: 19 THE MCSCF PROGRAM Previous: 19.10 Optimizing valence bond   Contents   Index   PDF

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