Dear All,
(thanks so much for kwant ;) )
I am wondering whether there is a mistake/typo in the docstring of the
PropagatingModes object.
The reason is the following: In a simple lead (specifically graphene
zigzag nanoribbon) at energy that excites 6 modes (only 3 with positive
derivative dE/dk),
when getting the `PropagatingModes` (either through physics.modes or by
the Smatrix), and I get the momenta and velocities, it looks like this:
In [35]: modes
Out[35]: <kwant.physics.leads.PropagatingModes at 0x2139805ecf8>
In [36]: modes.momenta
Out[36]:
array([-2.12874239, 2.0566145 , 2.06992722, 2.12874239, -2.0566145 ,
-2.06992722])
In [37]: modes.velocities
Out[37]:
array([-1.91098658, -2.24527103, -1.66541483, 1.91098658, 2.24527103,
1.66541483])
Now, the docstring of Propagating modes states:
The first half of the
modes have negative velocity, the second half have positive velocity. The
modes with negative velocity are ordered from larger to lower momenta, the
modes with positive velocity vice versa.
However, this is not what I see. The first half, with negative velocity,
is clearly sorted from smaller to bigger momenta, while the second half
(with positive velocity) is sorted from bigger to slower momenta. This
is the exact opposite of the docstring.
Thus I am writing this mail to see if I have misunderstood something or
if this is simply a typo mistake.
Best,
George
