Using pseudo-hydrogen in VASP results in the wrong format in CONTCAR

Question

I am using VASP to do the simulation of a slab, I used some pseudohydrogen to passivate the bottom side of the slab. After the structure optimization calculation, the CONTCAR I get looks like this:

 TiO2_mp-2657_slab_unitcell             
   1.0000000000000000     
     2.9691998959000001    0.0000000000000000    0.0000000000000000
     0.0000000000000000    6.5806999206999999    0.0000000000000000
     0.0000000000000000    0.0000000000000000   38.4453010559000035
   Ti   O    H.   H1
     8    16     1     1

The original POSCAR is:

 TiO2_mp-2657_slab_unitcell             
   1.0000000000000000     
     2.9691998959000001    0.0000000000000000    0.0000000000000000
     0.0000000000000000    6.5806999206999999    0.0000000000000000
     0.0000000000000000    0.0000000000000000   38.4453010559000035
   Ti   O    H.66   H1.33
     8    16     1     1

As shown above, the H.66 and H1.33 turn into H. and H1. Is this just a small bug of the input/output, or is it gonna affect the calculation results?

Answer 1

I could be wrong, but I am fairly certain that line of the CONTCAR technically doesn't matter. If you put a O instead of H, but put the potentials in the right order, you will get the right result even though the element is wrong. For visualization, it will definitely be wrong but I don't think the calculated result is wrong.

In tools such as ASE the potentials are derived from this line of the POSCAR though, so be careful.