Strange atomic volumes when the weight method is used

[hiro]

I have encountered a strange result while trying Bader v0.95a and I would like to know if anyone is having a similar problem.

I downloaded v0.95a (Mac binary) from the Bader website and tested the weight method by Yu and Trinkle on the C2H4a example, also from the website. The command was
% bader095a -b weight ../CHG_C2H4a
and ACF.dat looked like this:

# X Y Z CHARGE MIN DIST ATOMIC VOL
--------------------------------------------------------------------------------
1 6.2359100 3.9141200 5.1132900 4.0362403 0.4180409 1.4076448
2 5.3032600 4.3634500 5.9509200 3.9895170 0.4392981 8.7207286
3 7.2992600 4.0656400 5.3042500 0.9672925 0.2998894 0.9409419
4 5.5630100 4.9021400 6.8633400 0.9850735 0.2964324 7.8304858
5 5.9762200 3.3754300 4.2008600 1.0184654 0.2681500 14.3692100
6 4.2399100 4.2119500 5.7599500 0.9652454 0.3325264 14.7558330
--------------------------------------------------------------------------------
VACUUM CHARGE: 0.0382
VACUUM VOLUME: 893.7041
NUMBER OF ELECTRONS: 12.0000

As you can see, the charges are nearly equal between equivalent atoms, but the atomic volumes vary significantly. They are much smaller than ~24 on C and ~14.5 on H obtained with the neargrid method (at the same vacuum cutoff). This seems to be the case with several other examples I tested.

So I looked into weight_mod.f90. I could be wrong but it appears bdr%ionvol gets Bader volumes instead of atomic volumes. In the bader_weight_calc subroutine, bdr%ionvol is allocated bdr%nvols elements whereas it is allocated ions%nions elements in the cal_atomic_vol subroutine used by the neargrid method. I suppose it is necessary to add up Bader volumes for each atom at the end of bader_weight_calc after assign_chg2atom is called.

[graeme]

Thanks for this note and the analysis. I've done exactly what you suggested in v1.0:

bader -b weight CHG_C2H4a

GRID BASED BADER ANALYSIS (Version 1.0 01/11/17)

OPEN ... CHG_C2H4a
VASP4-STYLE INPUT FILE
DENSITY-GRID: 140 x 140 x 140
CLOSE ... CHG_C2H4a
RUN TIME: 1.01 SECONDS

SORTING CHARGE VALUES ... DONE
CALCULATING FLUX ... DONE

INTEGRATING CHARGES
0 10 25 50 75 100
PERCENT DONE: **********************
RUN TIME: 0.83 SECONDS

CALCULATING MINIMUM DISTANCES TO ATOMS
0 10 25 50 75 100
PERCENT DONE: **********************
RUN TIME: 0.08 SECONDS

WRITING BADER ATOMIC CHARGES TO ACF.dat
WRITING BADER VOLUME CHARGES TO BCF.dat

NUMBER OF BADER MAXIMA FOUND: 13
SIGNIFICANT MAXIMA FOUND: 13
VACUUM CHARGE: 0.0382
NUMBER OF ELECTRONS: 12.00000

-------------
cat ACF.dat
-------------


# X Y Z CHARGE MIN DIST ATOMIC VOL
--------------------------------------------------------------------------------
1 6.235910 3.914120 5.113290 4.036240 0.418041 23.684450
2 5.303260 4.363450 5.950920 3.989517 0.439298 23.530587
3 7.299260 4.065640 5.304250 0.967292 0.299889 14.758453
4 5.563010 4.902140 6.863340 0.985074 0.296432 14.660980
5 5.976220 3.375430 4.200860 1.018465 0.268150 14.905616
6 4.239910 4.211950 5.759950 0.965245 0.332526 14.755833
--------------------------------------------------------------------------------
VACUUM CHARGE: 0.0382
VACUUM VOLUME: 893.7041
NUMBER OF ELECTRONS: 12.0000

[hiro]

Thank you for the updated code.
Looks like the problem has been solved.