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Dear lammps users,

Dear lammps users,

I wanted to do crack simulation for Al2O3, and nonperiodic boundary

conditions are set for x and y direction, but ewald summation cannot be used

with nonperiodic boundaries, can you give me any suggestions to solve the

problem?

either use periodic boundaries or don't use ewald summation.

axel.

Note that you can still simulate a non-periodic structure in a periodic simulation box. The physical interpretation is an infinite periodic array of finite structures separated by vacuum. The larger the vacuum gap, the more closely it approximates the limit of an isolated structure, but also the larger the vacuum gap, the more kspace points are needed to achieve a desired accuracy level. The kspace_modify slab keyword can help with this, although I am not sure if it works correctly for two non-periodic directions (rod rather than slab geometry). In any case, you should test your simulation method carefully to ensure that it is free of finite-size artifacts.

Note that you can still simulate a non-periodic structure in a periodic

simulation box. The physical interpretation is an infinite periodic array

of finite structures separated by vacuum. The larger the vacuum gap, the

more closely it approximates the limit of an isolated structure, but also

the larger the vacuum gap, the more kspace points are needed to achieve a

desired accuracy level. The kspace_modify slab keyword can help with this,

the slab correction is only available for z direction, so it cannot be

used for two non-periodic directions.

although I am not sure if it works correctly for two non-periodic directions

(rod rather than slab geometry). In any case, you should test your

simulation method carefully to ensure that it is free of finite-size

artifacts.

if the rod is not too wide, using a long cutoff can be very

competitive if not superior in terms of performance and accuracy

compared to the coul/long with kspace solver setup, as interactions in

the non-periodic directions would be computed completely, the

neighborlists are still relatively short and you would not need to

compute kspace contributions for vacuum areas.

axel.

Sorry for not replying to your emails timely, I am still testing for an appropriate simulation method for my problem.

Thank you for your helpful advise.

Best regards,

FU

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