(c) 2017, Marcus Elstner, Karlsruher Institut für Technologie
All rights reserved

This work is licensed under the Creative Commons Attribution-ShareAlike 4.0
International License. To view a copy of this license, consult the LICENSE file
or visit http://creativecommons.org/licenses/by-sa/4.0/ .

NOTE: The rights holder(s) for this work explicitly require that the attribution
conditions of this license are enforced. Use in part or in whole of this data is
permitted only under the condition that the scientific background of the
Licensed Material will be CITED IN ANY PUBLICATIONS ARISING FROM ITS USE. The
required references are specified in this file and must be included in resulting works.


SPECIFIC PURPOSE PARAMETER SETS

name   requires    elements    
hhmod     mio          H-H 

short description
hhmod for proper description of H2
        

detailed description:

When fitting the repulsive energy to a reference atomization energy of the 
H2 molecule the H-H potentials turns out to be negative for certain 
interatomic distances. This might cause trouble in molecular dynamics 
simulation. If two hydrogen atoms come very close to each other they might 
irreversibly form a covalent bond within DFTB. Therefore, within the mio-set 
the H-H repulsive potential is shifted to be positive for all interatomic 
distances. This solves the molecular dynamics problem but causes a wrong 
description of H-H covalent bonds (which is only relevant for e.g. the H2 molecule). 
The "HHmod" parameters are specifically parameterized for the correct 
description of the H2 molecule with respect to atomization energy, bond length and
vibrational frequency.


RELEVANT PUBLICATIONS
[PRB98]   Phys. Rev. B 58 (1998) 7260.

REQUIRED REFERENCES
H-H-mod       [PRB98]  	Phys. Rev. B 58 (1998) 7260