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TOMBO Ver.2 Manual

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1.4 Calculation flow 10<br />

1.4 Calculation flow<br />

Flowchart of the first-principles molecular dynamics (MD) is shown in Fig. 1.5.<br />

Set initial atomic positions<br />

❄<br />

Assume initial charge density<br />

❄<br />

Initialize coefficients C λ i<br />

✲<br />

❄<br />

Calculate charge density<br />

❄<br />

Mix the charge density with<br />

that of the previous step<br />

Calculate the KS potential<br />

❄<br />

Calculate matrix ❄ elements<br />

❄<br />

Update Ci<br />

λ according to<br />

matrix diagonalization or<br />

steepest-descent method<br />

❄<br />

NO ✘✘✘✘✘✘✘<br />

✛ ✘❳❳❳❳❳❳❳❳❳❳❳❳❳❳❳❳❳❳<br />

✘ If |E new − E old | < precLDA<br />

✘✘✘✘✘✘✘✘✘<br />

YES<br />

❄<br />

Calculate forces on atoms<br />

❄<br />

Update atomic positions<br />

Check self-consistency<br />

Fig. 1.5 Flowchart of the first-principles MD. The convergence of the electronic states is<br />

checked by the difference between the total energies at the present and previous steps. If<br />

convergence is achieved, the atomic positions are updated by using the calculated force.

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