Code review comment for lp:~nickpapior/siesta/low-D-stress

1)

For 2D graphene I find the following dependence on the 2D stress tensor (directory is vacuum in Ang)

100/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
100/RUN.out-siesta: -0.104105 -0.000000 0.000000
100/RUN.out-siesta: -0.000000 -0.104441 0.000000
--
110/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
110/RUN.out-siesta: -0.104470 -0.000000 0.000000
110/RUN.out-siesta: -0.000000 -0.104806 0.000000
--
120/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
120/RUN.out-siesta: -0.104281 -0.000000 0.000000
120/RUN.out-siesta: 0.000000 -0.104617 0.000000
--
130/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
130/RUN.out-siesta: -0.104602 -0.000000 0.000000
130/RUN.out-siesta: -0.000000 -0.104938 0.000000
--
20/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
20/RUN.out-siesta: -0.104098 -0.000000 0.000000
20/RUN.out-siesta: 0.000000 -0.104434 0.000000
--
30/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
30/RUN.out-siesta: -0.105210 -0.000000 0.000000
30/RUN.out-siesta: -0.000000 -0.105546 0.000000
--
40/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
40/RUN.out-siesta: -0.104277 0.000000 0.000000
40/RUN.out-siesta: 0.000000 -0.104613 0.000000
--
50/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
50/RUN.out-siesta: -0.105209 0.000000 0.000000
50/RUN.out-siesta: 0.000000 -0.105545 0.000000
--
60/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
60/RUN.out-siesta: -0.104109 -0.000000 0.000000
60/RUN.out-siesta: -0.000000 -0.104445 0.000000
--
70/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
70/RUN.out-siesta: -0.104656 0.000000 0.000000
70/RUN.out-siesta: 0.000000 -0.104992 0.000000
--
80/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
80/RUN.out-siesta: -0.104286 -0.000000 0.000000
80/RUN.out-siesta: 0.000000 -0.104622 0.000000
--
90/RUN.out:siesta: 2D stress tensor (static) (eV/Ang**2):
90/RUN.out-siesta: -0.105208 0.000000 0.000000
90/RUN.out-siesta: 0.000000 -0.105544 0.000000

For a 1D carbon chain with directory being the vacuum along the two perpendicular directions
10/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
10/RUN.out-siesta: 0.000000 0.000000 0.000000
10/RUN.out-siesta: 0.000000 0.000000 0.000000
10/RUN.out-siesta: 0.000000 0.000000 7.196726
--
20/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
20/RUN.out-siesta: 0.000000 0.000000 0.000000
20/RUN.out-siesta: 0.000000 0.000000 0.000000
20/RUN.out-siesta: 0.000000 0.000000 7.198956
--
30/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
30/RUN.out-siesta: 0.000000 0.000000 0.000000
30/RUN.out-siesta: 0.000000 0.000000 0.000000
30/RUN.out-siesta: 0.000000 0.000000 7.196728
--
40/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
40/RUN.out-siesta: 0.000000 0.000000 0.000000
40/RUN.out-siesta: 0.000000 0.000000 0.000000
40/RUN.out-siesta: 0.000000 0.000000 7.206712
--
50/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
50/RUN.out-siesta: 0.000000 0.000000 0.000000
50/RUN.out-siesta: 0.000000 0.000000 0.000000
50/RUN.out-siesta: 0.000000 0.000000 7.196725
--
60/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
60/RUN.out-siesta: 0.000000 0.000000 0.000000
60/RUN.out-siesta: 0.000000 0.000000 0.000000
60/RUN.out-siesta: 0.000000 0.000000 7.198949
--
70/RUN.out:siesta: 1D stress tensor (static) (eV/Ang):
70/RUN.out-siesta: 0.000000 0.000000 0.000000
70/RUN.out-siesta: 0.000000 0.000000 0.000000
70/RUN.out-siesta: 0.000000 0.000000 7.211712

It is relatively stable but is dependent on the mesh and eggbox (here 400 Ry).

2) No, true. It is not an explicit equation for a slab. So I don't know if we should name it differently? "1/2D stress tensor (approximated) (static)"? or?