about inial spin in scattering region

[kinda]

I want to give some atoms initial spin in scattering region in 11.8. But I note that the initial spin must given betweeen -1 and 1. I don't know the reason. And what's the unit of spin in ATK? Thank you in advance.

[Anders Blom]

"Spin" doesn't have a unit since it's not an observable. What you specify as "initial spin" is the relative spin polarization, so it's dimensionless. Therefore it is also from -1 to 1, where 1 (-1) means maximal spin up (down).

See http://quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.initialspin.html for details.

[kinda]

I think you mean that 1 and -1 means spin up and spin down for a electron respectively. But for a particular element atom， there are some valent electrons in outmost orbits and each electron has a spin direction. Should i sum up all the spin directions to determine the total spin of the element atom.

[kinda]

I get what you mean in the help document. Thank you very much