the calculations of N2 molecule bond energy

[Paul]

Hi,
I want to calculate the N2 molecule bond energy , but the result is very bad, and has a big difference with experiments . And I can not find the reason .
Can you tell me why and how I should change the input files .
This is my input files and the result . Thanks.

ndtset 2 udtset 1 2
ixc -101130
acell:? 35 35 35 acell+? 2 2 2
ecut 31

natom?1 2
ionmov?1 2
optcell?1 0
ntime?1 50
tolmxf?1 5.0d-4
xcart?1 -1.0 0.0 0.0
1.0 0.0 0.0
toldff?1 5.0d-5
nband?1 7

natom?2 1
nsppol?2 2
occopt?2 2
nband?2 7 7
occ?2 1.0 1.0 1.0 0.0 0.0 0.0 0.0
1.0 1.0 0.0 0.0 0.0 0.0 0.0
toldfe?2 1.0d-6
xcart?2 0.0 0.0 0.0
spinat?2 0.0 0.0 1.0
wtk?2 1

#rprim 1 0 0
0 1 0
0 0 1

ntypat 1
znucl 7
typat 1 1
kptopt 0
nkpt 1
nstep 100
diemac 2.0

And the result is :
etotal1 -1.9912245688E+01
etotal2 -9.6592504941E+00
Ebond= 19.9122-2*9.65925=0.5937Ha=16.15ev
but the experiments is 9.8ev