Set the QM cell in QMMM

[Yuqi wang]

Dear all,

I try to combine QMMM and metadynamic in my research. But I encountered some difficulties.

In my research ,I want to explore the stable positions of hydrogen atom in silica. In order to speed up the metadynamic calculation, I try to add the QM cell in the system. The whole system is &SUBSYS/&CELL ABC 15 15 15. I  want to set a 5×5×5 cell in the middle of the whole syetem (the green cube).

However, I don't know how to set the &FORCE_EVAL/&QMMM/CELL.

In the description of the manual, ABC are based on Cartesian. In this case, the green 

 cube cannot be defined.  The size of the whole system(MM) is based on the origin, but the green cube(QM) seems to need to be translated. 

I wonder how to discribe the QS cell position when the cell is inside of the MM cell.Or is there any other way to achieve.

Thanks in advance

Sinerely 

Wang

[Marcella Iannuzzi]

Dear Wang,

The simulation box does not have a position in space, it is only a definition of a volume 

In QMMM if the QM box is not the same as the MM box, then the QM coordinates need to be centred in the QM box, which then will be the volume around these coordinates. 

 This volume needs to be large enough, depending on the type of QM/MM and QM/QM electrostatic interaction of choice, i.e., periodic, not periodic, type of coupling.

Refer to the following paper https://doi.org/10.1021/ct6001169

Regards

Marcella

[Yuqi wang]

Thanks a lot for your suggestion. 

But I encountered the problem of “CPASSERT failed ” while running CP2K.  

I tried  so many times, but none of them solved the problem.I don't know what caused this error.

 *******************************************************************************
 *   ___                                                                       *
 *  /   \                                                                      *
 * [ABORT]                                                                     *
 *  \___/                             CPASSERT failed                          *
 *    |                                                                        *
 *  O/|                                                                        *
 * /| |                                                                        *
 * / \                                               pw/pw_spline_utils.F:1086 *
 *******************************************************************************

Also I didn't understand what does “pw/pw_spline_utils.F:1086”  mean. Is it helpful to solve the problem?

Looking forward to your suggestions

Sinerely 

Wang