<div>Hello, everyone. As a benchmark test, I performed the vc-relax+vdW-DF calculations for graphite. The opitimized lattice constants seem to be unreasonable using vc-relax+vdW-DF. It is overestimated about about 29% for a. <span id="tran_0_0">I </span><span id="tran_0_1">don't </span><span id="tran_0_2">know what </span>the <span id="tran_0_3">problem </span><span id="tran_0_4">is.</span></div>
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<div>#############################################################################################<br> total stress (Ry/bohr**3) (kbar) P= -0.01<br> -0.00000002 0.00000000 0.00000000 0.00 0.00 0.00<br>
0.00000000 -0.00000002 0.00000000 0.00 0.00 0.00<br> 0.00000000 0.00000000 -0.00000007 0.00 0.00 -0.01</div>
<div><br> The maximum number of steps has been reached.</div>
<div> End of BFGS Geometry Optimization<br>Begin final coordinates<br> new unit-cell volume = 450.28054 a.u.^3 ( 66.72469 Ang^3 )</div>
<div>CELL_PARAMETERS (alat= 4.68000000)<br> 1.292794235 -0.000000090 0.000000000<br> -0.646397196 1.119592604 0.000000000<br> 0.000000000 0.000000000 3.034982637</div>
<div>ATOMIC_POSITIONS (crystal)<br>C -0.000001693 0.000001693 0.250000000<br>C 0.000001693 -0.000001693 0.750000000<br>C 0.333331648 0.666668352 0.250000000<br>C 0.666668352 0.333331648 0.750000000<br>
End final coordinates<br>######################################################################################</div>
<div> </div>
<div> </div>
<div> </div>
<div>&control<br> calculation = 'vc-relax'<br>! restart_mode='from_scratch',<br> prefix='graphite',<br> tstress = .true.<br> tprnfor = .true.<br> pseudo_dir = "/home/wangvei/works/quantum-espresso/pseudo",<br>
outdir = "./",<br> disk_io = 'none'<br> forc_conv_thr = 1.0e-3<br> nstep = 45 ,<br> etot_conv_thr = 1.0E-4 ,<br> forc_conv_thr = 1.0D-3 ,<br> iprint = 1 ,<br>
max_seconds = 36000 ,<br> dt = 100 ,<br>/<br>&system<br> ibrav = 4<br> celldm(1) = 4.68<br> celldm(3) = 2.70<br> nat = 4<br> ntyp = 1<br>
occupations = "smearing",<br> smearing = "gaussian",<br> degauss = 0.002D0,<br> ecutwfc = 40.0<br> ecutrho = 200<br> input_dft = 'vdw1'<br>/<br>&electrons<br>
conv_thr = 1.0d-8<br>/<br>&ions<br>/<br>&cell<br> press_conv_thr = 0.0D0<br> press = 0.D0<br> cell_dynamics = 'bfgs'<br>! cell_dofree = 'z'<br>/<br>ATOMIC_SPECIES<br>
C 12.00 C.pbe-paw_kj.UPF<br>ATOMIC_POSITIONS {crystal}<br> C 0.00000 0.00000 0.25000<br> C 0.00000 0.00000 0.75000<br> C 0.33333 0.66667 0.25000<br> C 0.66667 0.33333 0.75000<br>K_POINTS automatic<br>
9 9 4 0 0 0<br></div></span>