I am trying to do some vc relax calculations under high pressure(0-40 GPa) on LiC6. Should the 'press' value under the &CELL card be changed accordingly? What is generally the unit of pressure here? Is any unit conversion required?

I am attaching a sample input file for calculations at 40 GPa--

&control

calculation='vc-relax',

restart_mode='from_scratch',

prefix='vc-relax_90_f4e5'

pseudo_dir = './../',

forc_conv_thr = 1.0d-4,

etot_conv_thr = 1.0d-5,

nstep = 1000

/

&system

ibrav=4,

!space_group = 1,

celldm(1)= 8.169834,

celldm(3)= 0.866324,

!a = 4.32329,

!c = 3.74537,

nat= 7,

ntyp= 2,

vdw_corr = 'dft-d3',

dftd3_version = 4,

ecutwfc = 90

ecutrho = 900

occupations = "smearing"

smearing = "gaussian"

degauss = 0.001

/

&electrons

conv_thr =1.0d-8

/

&ions

ion_dynamics = 'bfgs'

/

&cell

cell_dynamics = 'bfgs',

cell_dofree = 'ibrav',

press = 40.0,

press_conv_thr = 0.1

/

ATOMIC_SPECIES

C 12.0107 C.pbe-n-rrkjus_psl.1.0.0.UPF

Li 6.9410 Li.pbe-sl-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS crystal

C -0.0000000043 0.3335500011 0.5000000318

C 0.3335499898 0.0000000001 0.5000000318

C 0.6664500095 0.6664499950 0.5000000318

C -0.0000000197 0.6664499950 0.5000000318

C 0.6664500481 0.0000000001 0.5000000318

C 0.3335499942 0.3335500011 0.5000000318

Li 0.0000000000 0.0000000000 0.0000000000

K_POINTS AUTOMATIC

4 4 4 1 1 1