### Wrong Berry phase with LOBPCG

Posted:

**Mon Mar 25, 2019 6:53 pm**Dear all,

I compiled abinit 8.10.2 on the anselm cluster using the following config parameters

I am using norm-conserving pseudopotentials downloaded from the abinit website.

I ran a berryphase calculation in the presence of electric field testing different combinations of fftalg and wfoptalg options to improve the speed of the calculation. Unfortunately, only the wfoptalg=0 (file out_1 attached) gives reliable values of the forces on the atoms and the polarization, but it's the slowest. Whenever the LOBPCG algorithm is active, the forces on the atoms are larger and the polarization is smaller by 2-3 order of magnitude with respect to the case in which wfoptalg=0. In the examples I posted here, with wfoptalg!=0 I used nbdblock=1 to reduce to the minimum numerical instabilities but I get the same differences in the forces and polarization which I get with nbdblock>1. I also tested ortalg=2 with wfoptalg!=0 (file out_4 attached) but with no results.

I need to do several of this calculations to compute the phonons with the frozen phonon approach. Unfortunately, the use of wfoptalg=0 requires a too large computation time and makes this approach prohibitive; on the other side, the DFPT approach has other issues; the combination of wfoptalg=114 with fftalg0=312 gives the best computation time and it would be the ideal one if it worked.

Please, note also that the run in out_2 and out_4 didn't converge because they reached the limit of 1000 scf steps; however, both are really close to the convergence and no improvement is expected to make the forces and polarization values comparable to those in the out_1 file.

I am not sure, but this problem seems to be related to this topic I opened some time ago.

Output files are large and cannot be uploaded here. This is the link to download them.

Thanks a lot in advance for your kind help.

Antonio

I compiled abinit 8.10.2 on the anselm cluster using the following config parameters

- Code: Select all
`./configure --prefix=/home/acamm/bin/abinit-8.10.2 \`

--enable-mpi --enable-mpi-io --enable-optim="aggressive" \

--enable-mpi-inplace \

--enable-zdot-bugfix="yes" \

--with-fft-flavor="fftw3-mpi" \

--with-fft-libs="-lfftw3 -lfftw3f -lfftw3_mpi -lfftw3f_mpi -lfftw3_threads -lfftw3f_threads" \

--with-fft-incs="-I/apps/all/FFTW/3.3.7-gompi-2018a/include" \

--with-linalg-libs="-lscalapack -lopenblas" \

--with-dft-flavor="libxc" \

--with-libxc-libs="-L/home/acamm/local/lib/libxc-3.0.0/lib -lxcf90 -lxc" \

--with-libxc-incs="-I/home/acamm/local/lib/libxc-3.0.0/include" \

FC=mpif90 \

CC=mpicc \

CXX=mpicxx

I am using norm-conserving pseudopotentials downloaded from the abinit website.

I ran a berryphase calculation in the presence of electric field testing different combinations of fftalg and wfoptalg options to improve the speed of the calculation. Unfortunately, only the wfoptalg=0 (file out_1 attached) gives reliable values of the forces on the atoms and the polarization, but it's the slowest. Whenever the LOBPCG algorithm is active, the forces on the atoms are larger and the polarization is smaller by 2-3 order of magnitude with respect to the case in which wfoptalg=0. In the examples I posted here, with wfoptalg!=0 I used nbdblock=1 to reduce to the minimum numerical instabilities but I get the same differences in the forces and polarization which I get with nbdblock>1. I also tested ortalg=2 with wfoptalg!=0 (file out_4 attached) but with no results.

I need to do several of this calculations to compute the phonons with the frozen phonon approach. Unfortunately, the use of wfoptalg=0 requires a too large computation time and makes this approach prohibitive; on the other side, the DFPT approach has other issues; the combination of wfoptalg=114 with fftalg0=312 gives the best computation time and it would be the ideal one if it worked.

Please, note also that the run in out_2 and out_4 didn't converge because they reached the limit of 1000 scf steps; however, both are really close to the convergence and no improvement is expected to make the forces and polarization values comparable to those in the out_1 file.

I am not sure, but this problem seems to be related to this topic I opened some time ago.

Output files are large and cannot be uploaded here. This is the link to download them.

Thanks a lot in advance for your kind help.

Antonio