ABINIT Discussion Forums

Greetings,
I have been trying to learn more about Berry phase calculations in a finite electric field. First, I tried the finite electric field calculation for AlAs in the tutorials without problem. I then tried to adopt the same procedure for GaAs. I have set the polarization direction to be 111 and am using a rhombohedral primitive cell for the structure. While I doubt it matters, I have also optimized the cell size using the HGH PS within the LDA. For the Berry phase, I first calculate the SCF 8x8x8 MP grid with 4 shift vectors and calculate the Berry phase in zero field and pass the resulting wavefunction to the next dataset and gradually turn on the efield with berryopt 4. Running the serial version of abinit with this input always results in a crash at the start of the Berry phase calculation. I have tried this with different k-point meshes to no avail. Any suggestions would be greatly appreciated.





ETOT 8 -8.6674496284773 -3.375E-13 3.561E-08 4.435E-11
scprqt: <Vxc>= -3.2553761E-01 hartree
newvtr : enter
newvtr : ispmix,nfft,nfftmix= 1 91125 91125

Pulay update with 7 previous iterations:
mixing of old trial potential : alpha(m:m-4)= 1.09 -0.969E-01 0.946E-02 -0.383E-03 -0.478E-04

ITER STEP NUMBER 9
vtorho : nnsclo_now= 1, note that nnsclo,dbl_nnsclo,istep= 0 0 9
leave_test : synchronization done...
vtorho: loop on k-points and spins done in parallel
vtorho: echo density
Total charge density [el/Bohr^3]
, Maximum= 1.0601E-01 at reduced coord. 0.1778 0.1778 0.4889
, Minimum= 2.6512E-05 at reduced coord. 0.0000 0.0000 0.0000
, Integrated= 8.0000E+00
mkdenpos : enter
xc_denpos= 9.99999999999999999E-015
ETOT 9 -8.6674496284769 3.606E-13 6.064E-09 1.030E-13
scprqt: <Vxc>= -3.2553761E-01 hartree

At SCF step 9, etot is converged :
for the second time, diff in etot= 3.606E-13 < toldfe= 1.000E-12

Computing the polarization (Berry phase) for reciprocal vector:
0.12500 0.00000 0.00000 (in reduced coordinates)
-0.01196 0.01196 0.01196 (in cartesian coordinates - atomic units)
Number of strings: 256
Number of k points in string: 8

berryphase_new : BUG -
For k-point # 1,
the determinant of the overlap matrix is found to be 0.

berryphase_new : BUG -
For k-point # 1,
the determinant of the overlap matrix is found to be 0.
Action : contact ABINIT group.
Action : contact ABINIT group.


.Delivered 15 WARNINGs and 15 COMMENTs to log file.

leave_new : decision taken to exit ...
DATA TYPE INFORMATION:
REAL: Data type name: REAL(DP)
Kind value: 8
Precision: 15
Smallest nonnegligible quantity relative to 1: 0.22204460E-15
Smallest positive number: 0.22250739-307
Largest representable number: 0.17976931+309
INTEGER: Data type name: INTEGER(default)
Kind value: 4
Bit size: 32
Largest representable number: 2147483647
LOGICAL: Data type name: LOGICAL
Kind value: 4
CHARACTER: Data type name: CHARACTER Kind value: 1
==== Using MPI-2 specifications ====
MPI-IO support is ON
xmpi_tag_ub ................ 2147483647
xmpi_bsize_ch .............. 1
xmpi_bsize_int ............. 4
xmpi_bsize_sp .............. 4
xmpi_bsize_dp .............. 8
xmpi_bsize_spc ............. 8
xmpi_bsize_dpc ............. 16
xmpio_bsize_frm ............ 4
xmpi_address_kind .......... 8
xmpi_offset_kind ........... 8

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

=== Build Information ===
Version : 6.12.3
Build target : x86_64_linux_gnu4.5
Build date : 20120902

=== Compiler Suite ===
C compiler : gnu4.5
CFLAGS : -g -O2 -mtune=native -march=native -mfpmath=sse
C++ compiler : gnu4.5
CXXFLAGS : -g -O2 -mtune=native -march=native -mfpmath=sse
Fortran compiler : gnu4.5
FCFLAGS : -g -ffree-line-length-none -Wstrict-aliasing=2
FC_LDFLAGS :

=== Optimizations ===
Debug level : basic
Optimization level : standard
Architecture : intel_xeon

=== MPI ===
Parallel build : yes
Parallel I/O : yes
Time tracing : no
GPU support : no

=== Connectors / Fallbacks ===
Connectors on : yes
Fallbacks on : yes
DFT flavor : libxc-fallback+atompaw-fallback+bigdft-fallback+wannier90-fallback
FFT flavor : none
LINALG flavor : mkl
MATH flavor : none
TIMER flavor : abinit
TRIO flavor : netcdf-fallback+etsf_io-fallback

=== Experimental features ===
Bindings : no
Exports : no
GW double-precision : no

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I am answering my own question which leads to yet another question. First, the reason the Berry phase calculation crashed was that my lattice constant was too small. Replacing the 10.45 (Bohr) value in the original GaAs input file with a value of 10.6 Bohr allows the Berry phase calculation to run to completion.

My confusion stems from the fact that I optimized the structure with respect to volume (with so_psp 2 2, nspinor 2) with spin-orbit turned on. At first I thought it might be an error in the force routine, but even changing the acell value in steps in different calculations leads to the same 10.45 Bohr value. Using this value in the Berry phase leads to a crash, but using the experimental value of 10.67 Bohr works. Does this mean that spin-orbit calculations are flaky? Does anyone have any insight?

Thanks!

Again the real problem is the spinor code for the Berry's phase in version 6.12.3. I just ran GaAs with nspinor 2, HGH pseudo's so spin orbit coupling on, with berryopt -1 followed by berryopt 4 and a finite efield, parallelized over k points, on version 7.0.1 and it worked fine-- ;)