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<div><span></span>Dear all,</div><div> Physically force can be denoted by F(R)= - dE/dR, and Helleman-Feyman theory is employed in DFT to evaluate force. <font color="#ff0000">In numerical routine of Pwscf code</font>, does force equal -dE/dR or dE/dR?</div><div><br></div><div>Jiqiang Li</div>
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