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<p><span style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 12.8px;">Dear All,</span></p>
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I am trying to run molecular dynamics simulations (Born-Oppenheimer and Car-Parrinello) of titanium at various temperatures using position and velocity input data from LAMMPS. I have successfully run such simulations with aluminum, but titanium has proved troublesome
thus far. It seems that no matter what I do, the first conjugate gradient step experiences a missed minimum, converges, and then diverges on the second step (with ortho going bananas). </div>
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So far, I have tried reducing the timestep (to 1-5 au), increasing the number of max iterations for ortho (50-100), Gram-Schmidt orthogonalization, reducing the energy convergence threshold (10^-6), and two different pseudopotentials (pz-hgh and pz-sp-hgh),
and different configurations from classical code. None of these variations have changed the result. Each time, there is a missed minimum (case 3) in CG before the first step converges followed by a second step that diverges.I even tried using the converged
first step as a starting point for Car-Parrinello MD, but that still fails to converge due to ortho going bananas. </div>
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Can anyone help me understand what is going wrong and how I might fix this problem?</div>
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<div style="font-size: 12.8px;">Thanks,</div>
<div style="font-size: 12.8px;">Nicholas Walker</div>
<div style="font-size: 12.8px;">Louisiana State University</div>
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