gcc version 4.9.4 gives a strict overflow warning under -O3 optimization. This occurs in the src/fraction.c file. However other versions seem fine. Obviously this isn't an actual problem (just remove the -Werror tag). However, from a technical standpoint I'd love to understand exactly why this is being caused.

High Priority

• Bilayer support
• Test suite
• Additional documentation
• Better command line options

Low Priority

• man pages
• interactive mode

Currently the chalcogen coordinates are incorrect for the both the 1T and 2H type structures. As a result, until this is fixed this program should NOT be used.

When generating a series of POSCAR files with uni-axial strain the second line of the POSCAR unit cell matrix is always slight wrong. As an example, he is the hexagonal unit cell for base lattice parameter of a = 5.000 where the second generated structure is -0.02 Ang compression along only the a-axis.

Initial cell (a=5.000 Ang)

   5.000000000                0.000000000                0.000000000
   -2.500000000                4.330127019                0.000000000
   0.000000000                0.000000000                23.600000000

Compressed cell (a=4.980 Ang)

   4.980000000                0.000000000                0.000000000
   -2.490000000                4.330127019                0.000000000
   0.000000000                0.000000000                23.600000000

As can be checked quickly, while the a-axis is compressed correctly, the b-axis is not the proper 5.000 Ang and instead there is a small compression along the x direction of that axis.