QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: hhspace on March 4, 2009, 04:00

Title: About the molecular unit cell!!
Post by: hhspace on March 4, 2009, 04:00

Hello everyone,
       I have some questions about the the molecular unit cell. The manual tells us that the molecular unit cell is automatically chosen such that there are no matrix elements between atoms in adjacent cells. Here I want to kown what "automatically" mean and whether it is related to the basis range of elements. If it is, how do you choose the distance to ensure no matrix elements between atoms in adjacent cells?!  And could you offer data about the basis range of elements?  Thank you very much.

Title: Re: About the molecular unit cell!!
Post by: Nordland on March 4, 2009, 09:12

The unitcell is created by placing a ball on each atom, where each ball has the radius of the longest orbital on the specific atom. Then a bounding box is calculated, and
this bounding box is then scaled up by the padding factor explained in the manual: Here (http://quantumwise.com/documents/manuals/ATK-2008.10/ref.poissonequationparameters.html).
The range of the elements depend on your basis set parameters, so the basis range of each element depends on your parameters.