<div>Dear QE users,</div>
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<div>Why are the total energy and press of the final step of vc-relax calculation different from those of the scf calculation using the same structure?  Especially for the values of press, w<span id="tran_0_0">hat </span>makes <span id="tran_0_1">this </span><span id="tran_0_2">great </span><span id="tran_0_3">difference</span> between the final step of vc-relax calculation and the final scf calculation (after the vc-relax calculation)?</div>

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<div>(1) For the final step of vc-relax calculation, the press and total energy are:</div>
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<div>!    total energy              =     -73.74310183 Ry<br></div>
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<div>          total   stress  (Ry/bohr**3)                   (kbar)     P=   -0.03<br>  -0.00000009   0.00000001   0.00000000         -0.01      0.00      0.00<br>   0.00000001  -0.00000008   0.00000000          0.00     -0.01      0.00<br>
   0.00000000   0.00000000  -0.00000048          0.00      0.00     -0.07</div>
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<div>(2) For the final scf calculations, the press and total energy are:<br></div>
<div>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>!    total energy              =     -74.60031750 Ry</div>
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<div>          total   stress  (Ry/bohr**3)                   (kbar)     P=  638.94<br>   0.00760001  -0.00000151   0.00000000       1118.00     -0.22      0.00<br>  -0.00000151   0.00759826   0.00000000         -0.22   1117.74      0.00<br>
   0.00000000   0.00000000  -0.00216804          0.00      0.00   -318.93<br>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</div>
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<div>Regards,</div>
<div>WANG</div>
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