Requests for technical support from the VASP group should be posted in the VASP-forum.

LORBIT

From Vaspwiki
Jump to navigationJump to search

LORBIT = 0 | 1 | 2 | 5 | 10 | 11 | 12
Default: LORBIT = None 

Description: LORBIT, together with an appropriate RWIGS, determines whether the PROCAR or PROOUT files are written.


LORBIT RWIGS tag files written
0 required DOSCAR and PROCAR
1 required DOSCAR and lm-decomposed PROCAR
2 required DOSCAR and lm-decomposed PROCAR + phase factors
5 required DOSCAR and PROOUT
10 ignored DOSCAR and PROCAR
11 ignored DOSCAR and lm-decomposed PROCAR
12 ignored DOSCAR and lm-decomposed PROCAR + phase factors
13 ignored DOSCAR and lm-decomposed PROCAR + phase factors, choose best projector for each band
14 ignored DOSCAR and lm-decomposed PROCAR + phase factors, choose single projector for interval EMIN,EMAX

Remarks:

LORBIT=13 and LORBIT=14 are only supported by version >=5.4.4. For LORBIT >= 11 and ISYM = 2 the partial charge densities are not correctly symmetrized and can result in different charges for symmetrically equivalent partial charge densities. This issue if fixed as of version >=6. For older versions of vasp a two-step procedure is recommended:

  • 1. Self-consistent calculation with symmetry switched on (ISYM=2)
  • 2. Recalculation of the partial charge density with symmetry switched off (ISYM=0)

To avoid unnecessary large WAVECAR files it recommended to set LWAVE=.FALSE. in step 2

The phase factors written by VASP can usually only be used as a qualitative measure of the projection of the orbitals into the atomic sphere. The main issue is that most VASP POTCAR files have two or three projectors per l-quantum number, and projecting an orbital onto two projectors will obviously yield two complex numbers. VASP combines these two numbers into a single number. The precise algorithms differ in different versions of VASP, and we recommend that you inspect the source code for more details. From vasp.6 onward, a new improved scheme has been implemented and can be selected using LORBIT=14. In this case, VASP first selects a single projector for each l-quantum number by linearly combining all projectors with the same l-quantum number. This is done in such a way that the new projector is optimally chosen to represent the calculated orbitals in the energy interval specified by ENMAX and ENMIN. In the second step, VASP projects onto these optimized projectors yielding a single complex number for each orbital, site and l-quantum number, which is written to the PROCAR file. For details we also refer to [1]. LORBIT=12 should no longer be used except for qualitative calculations. LORBIT=13 chooses the projectors also automatically, but allows for different optimal linear combinations for each orbital. Note that this is generally not desirable, since the resultant projection is not compatible with the required properties of a projection operator (a projection operator needs to use energy and orbital independent projectors). Hence do not use LORBIT=13 for anything but a qualitative analysis.

  • If LORBIT is set the partial charge densities can be found in the OUTCAR
total charge     

# of ion       s       p       d       tot
------------------------------------------
    1        1.514   0.000   0.000   1.514
    2        0.123   0.345   0.000   0.468

Here the first column corresponds to the ion index , the s, p, d,... columns correspond to the partial charges for defined as

The are obtained from the projection of the (occupied) wavefunctions onto spherical harmonics that are non zero within spheres of a radius RWIGS centered at ion and the last column is the sum .

Note that depending on the system an "f" column can be found as well.

  • In case of collinear calculations (ISPIN=2) the magnetization densities are written to the OUTCAR
magnetization (x)
 
# of ion       s       p       d       tot
------------------------------------------
    1        0.000   0.000   0.000   0.000
    2        0.000   0.245   0.000   0.245

Here the magnetization density (projection axis is the z-axis) is calculated from the difference in the up and down spin channel

  • In case of non-collinear calculations (LNONCOLLINEAR=.TRUE.) the lines after "total charge" correspond to the diagonal average

of the density tensor

which is determined from the projected components

of the spinor

Similarly, the lines after "magnetization (x)" correspond to the partial magnetization density projected onto the x direction and two additional entries "magnetization (y)", "magnetization (z)" are written for the y and z direction and are calculated from the three Pauli matrices

via

References

Related Tags and Sections

RWIGS, PROCAR, PROOUT, DOSCAR

Examples that use this tag


Contents