Re: scf.Ngrid estimate ( No.1 ) 
 Date: 2020/03/31 02:22
 Name: Naoya Yamaguchi
 Hi,
You may refer to the following: http://www.openmxsquare.org/forum/patio.cgi?mode=view&no=1543
>Is there a file where the code prints the employed planewave grid? A source file "truncation.c" outputs the used grid. You can refer to the following part of "truncation.c" for estimation of the number of grids: if (Ngrid_fixed_flag==0){
/* find proper N1, N2, and N3 */ (Omission) }

Re: scf.Ngrid estimate ( No.2 ) 
 Date: 2020/03/31 11:16
 Name: T. Ozaki
 Hi,
Instead of scf.Ngrid, if you specify the following keyword:
scf.energycutoff 120.0
you may see, e.g., the following information in the standard output:
Required cutoff energy (Ryd) for 3Dgrids = 120.0000 Used cutoff energy (Ryd) for 3Dgrids = 113.2041, 113.2041, 113.2041 Num. of grids of a, b, and caxes = 64, 64, 64
From the line: "Num. of grids of a, b, and caxes = 64, 64, 64", you can get the numbers of grids which nearly satisfy the required cutoff energy. Starting from the numbers, you can modify a proper set of numbers.
If the cell volume charges largely during the cell relaxation, and you want to investigate the energetics, you need to make sure that almost a same accuracy is achieved with respect to the number of grids, which can be confirmed by looking the the cutoff energy in the standard output, for all the optimized structures. Otherwise, your calculations may not be reliable.
Regards,
TO

Re: scf.Ngrid estimate ( No.3 ) 
 Date: 2020/04/02 03:14
 Name: Luca Sementa
 Dear Prof. Ozaki and dear Naoya
thank you for your answer! Best Regards. Luca

