Question about the classical BMHFT potential

[abdullahb...@gmail.com]

Dear CP2K users,

For the classical BMHFT potential, the C_6 (C parameter) and C_8 (D parameter) terms are multiplied by the Tang-Toennies damping functions, i.e. f_6 and f_8 (J. Phys. Chem. B, Vol. 112, No. 4, 2008). 

For this, an "ORDER" term (in CP2K) of 6 is needed for f_6 and 8 is needed for f_8. However, for defining this potential between two atoms, only a single "ORDER" term can be defined, for example, like this:

&BMHFTD

        atoms Cl Cl

        A 100.00000

        B 2.89128

        C 4.88053

        D 45.84421

        BD 3.21254

        RCUT 10.0

        ORDER 6

 &END BMHFTD

I am curious to know whether it is possible to set an ORDER for 6 for the f_6 term, which is then multiplied by the C_6 term; and an order of 8 for the f_8 term, which is then multiplied by the C_8 term. I tried the below input file format, but it does not work as CP2K (ver 5.1) stops reading the file and gives an error cause of the missing D parameter in the first part:

&BMHFTD

        atoms Cl Cl

        A 100.00000

        B 2.89128

        C 4.88053

        BD 3.21254

        RCUT 10.0

        ORDER 6

&END BMHFTD

&BMHFTD

        atoms Cl Cl

        D 45.84421

        BD 3.21254

        RCUT 10.0

        ORDER 8

&END BMHFTD

Error:

 *******************************************************************************

 *   ___                                                                       *

 *  /   \                                                                      *

 * [ABORT]                                                                     *

 *  \___/    Value requested, but no value set getting value from keyword D of *

 *    |                               section BMHFTD                           *

 *  O/|                                                                        *

 * /| |                                                                        *

 * / \                                        input/input_section_types.F:1303 *

 *******************************************************************************

Any suggestions would be greatly appreciated.

Thank you.

Best Regards,

Abdullah Bin Faheem