VASP Forum

I have designed a code to directly call the libMBD twice, and found that it can work successfully. Moreover, I have checked several points and noticed that during the first ionic step (I also tested with a static calculation), the apparently normal calculation in fact does not compute the vdW energy, as shown below in the OUTCAR file. Furthermore, when I moved the two lines under CASE(14) from the first position to the second in vdwforcefield.F, the structural optimization with IVDW=14 could complete successfully. However, all vdW energies and gradients became zero. Therefore, I believe the problem should lie in either libmd.F or vdwforcefield.F. The following is the corresponding result extracted from the OUTCAR file.
FORCE on cell =-STRESS in cart. coord. units (eV):
Direction XX YY ZZ XY YZ ZX
--------------------------------------------------------------------------------------
Alpha Z 20.71241 20.71241 20.71241
Ewald 11137.71754 11137.73871-12224.71345 0.00004 0.00000 0.00000
Hartree 11324.13471 11324.15579-11242.42892 0.00000 -0.00000 0.00000
E(xc) -134.97114 -134.95777 -135.87443 -0.00000 0.00000 0.00000
Local -23027.07751-23027.03326 22895.15380 -0.00003 0.00000 0.00000
n-local 257.35542 257.31064 265.25763 1.38537 0.00003 -0.00000
augment -58.99432 -58.99793 -60.24963 0.00000 -0.00000 0.00000
Kinetic 469.58608 469.54860 466.45144 0.71598 -0.00005 0.00000
Fock 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
vdW 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
-------------------------------------------------------------------------------------

Thanks again for investigating the problem. Yes, there is indeed a severe bug in libmbd.F. I did not test properly this interface to libMBD that I wrote. I will try to fix the issue as soon as possible and post the fix.

The bug fix is provided in the attached file. The modifications are in vdwforcefield.F and libmbd.F. To apply the patch, unzip the file and do the following:

cd /path/to/vasp.6.5.1
patch -p1 < /path/to/patch.txt

Then, recompile VASP. Please, tell me if there is still a problem.

Thank you very much for having reported the problem.

Thanks!