[Pw_forum] Some questions about non-collinear calculation and penalty function

[Sahar Mirshamsi]

Hi all,
I have some questions regarding non-collinear calculation and using
penalty function in pwscf.
1)	In constaint_magnetization ='atomic', is starting magnetization as the
target magnetization? I have read this post  
http://www.democritos.it/pipermail/pw_forum/2009-December/015342.html 
and also in input.f90 I found 
           mcons(1,nt) = starting_magnetization(nt) * SIN( theta ) * COS(
phi )
           mcons(2,nt) = starting_magnetization(nt) * SIN( theta ) * SIN(
phi )
           mcons(3,nt) = starting_magnetization(nt) * COS( theta )
 So it means both magnitude and direction of atomic magnetizations are
constrained, is this correct?
2)	If above statement is correct, then the same problem as posted in above
link will still exist,  since starting_magnetization=m/n, then for
constraining the magnitude of magnetization to desired value, we should
multiply the magnitude of magnetization by charge and then replace it as
starting_magnitization, is this correct?
3)	What is the relation between charge and magnetization printed in scf
calculation with those which we can get with using projwf.x, I expect they
should get almost same numbers but in scf output for carbons in Graphene
nanoribbon I get charge=0.6 and magnetization=0.1 while in projwf.x output
I get charge=4 and polarization=0.2-0.3 which the latest one makes more
sense.
4)	Also, in some cases of non-collinear calculation with using penalty
function, when I track "estimated scf accuracy" it is decreasing till
reaching the threshold  and stopping the job while "total energy" is
oscillating in some range instead of converging to a number , any idea
what's the problem?
5)	The total energy printed in scf calculation does not include constraint
energy, right? It's just energy of the structure with the constraint
configuration of magnetizations, right?
I appreciate any help in finding the answers of these questions.

Sahar Mishamsi
Quantum Theory Project and Physics Department,
University of Florida