Development progress. about wavecar_rs

[Ionizing]

TODOs (Jul 9 2020) :

• API invoking should be like:

Wavecar::from_file("path/to/wavecar/")
  .get_wavefunction_in_realspace(ispin, ikpoint, iband, ngrid)
  .apply_phase(r0)
  .normalize()
  .save_as_chgcar()

or

Wavecar::from_file("path/to/wavecar/")
  .get_wavefunction_in_realspace(ispin, ikpoint, iband, ngrid)
  .apply_phase(r0)
  .normalize()
  .into_charge_density()

A helper trait may be useful;

• Add a function that allow user to set the vasp type in order to resolve the failure in determining the gamma only WAVECAR;
• And a function like get_wavefunction_in_realspace without requiring ngrid should be implemented, in order to simplify the invoking; Done via get_wavefunction_in_realspace_dn, where dn means 'default ngrid'.
• Calculate the E-fermi from WAVECAR if we cannot find it from WAVECAR directly; Cannot be calculated without k-points' weights information
• Maybe we should use [u64; 3] to store ngrid; REJECTED
• Struct of WaveFunction should be designed carefully;
• Save wave function as CHGCAR function, sign of coefficient should be reserved;
• Save charge density as PARCHG function, |\psi|^2 should be used; Need to be done with vaspchg_rs
• A function that selecting multiple [spins/spinors, kpoints, bands] and calculate the total charge density;

[Ionizing]

GUI related

• Framework: gtk-rs, gtk's: tutorial

Won't implement. Maybe create another crate is needed to do this.

[Ionizing]

• Add a binary to list the WAVECAR information. Will be implemented in the NEAR future