QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: GJK on February 27, 2014, 03:19

Title: Boundary conditions -reg
Post by: GJK on February 27, 2014, 03:19

Hi,

In ATK 12.8 we are having three options in the Poisson Solver
1.Multigrid
2.FF2D
3.FFT

What solver should be selected for
1.Molecular Optimization
2.Device Optimization
3.Bulk optimization

Thanks in Advance

Title: Re: Boundary conditions -reg
Post by: Umberto Martinez on February 27, 2014, 11:22

device: use FFT2D unless you have spatial regions, then Multigrid.
bulk: FFT unless it is charged. In that case you will need Multigrid
molecule: Multigrid, multipole

then there are some special cases that you may consider, see for example the slab calculations in this tutorial: Tuning the work function of silver by deposition of ultrathin oxide layers (http://quantumwise.com/publications/tutorials/mini-tutorials/244)

Title: Re: Boundary conditions -reg
Post by: GJK on March 2, 2014, 17:01

Kindly explain me about spatial regions in a device and about multipole

Title: Re: Boundary conditions -reg
Post by: GJK on March 3, 2014, 18:32

Hi,

Kindly provide me an explanation of your following reply-
device: use FFT2D unless you have spatial regions,
bulk: FFT unless it is charged
molecule: Multigrid, multipole

Give some references or suggestions

Thanks in advance