About Non-Cubic Box

[pinkpig85]

I made a non-cubic; the lattice vector is shown below.

15.0000
1.3481 0.0000 0.0000
0.2891 0.5008 0.0000
0.0000 0.0000 1.0000

Incar

general:
system = ag-ptcda
ISTART = 1
ICHARG = 0
ENCUT = 400.0
ISMEAR = 2
SIGMA = 0.1;
ISIF = 0
NELMIN = 8
EDIFF = 1E-5
EDIFFG = -0.02
NSW = 150
MAXMIX = 80
IBRION = 1
NFREE = 10
ALGO = Fast
LREAL = A
NSIM = 4

The K-point was derived from Material Studio's castep module, which is 1*3*1 (Medium) .
During the relaxation process, the structure became disordered and I have to kill the job after several steps.
The whole system has 84 atoms, which is not very large. And I have successfully performed a similar calculation but with a cubic box.
I wonder if there is any special caution for the none-cubic box, for instance the selection of k points.

Thanks!