Questions tagged [variational-principle]

For questions related to variational methods in matter modeling.

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7 votes
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How is the error in a wavefunction related to the error in energy?

While studying the variational method in McQuarrie's Quantum Chemistry, I came across the following problem: to relate the difference between an approximation $\phi$ and the exact ground-state wave ...
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25 votes
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How do you calculate the "true" chemical potential in classical density functional theory?

In classical density functional theory, one traditionally calculates the chemical potential by taking the variational derivative, \begin{equation} \mu_{i} = \frac{\delta F}{\delta \rho_{i}}\tag{1} \...
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16 votes
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How does a complete basis set remove Pulay forces/stress?

When finding nuclear forces for the true electronic wavefunction, thanks to the Hellmann-Feynman theorem we only need to consider explicit derivatives with respect to the nuclear coordinates $\mathbf{...
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21 votes
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QMC calculation of the equation of state of metals

Is diffusion/variational quantum Monte Carlo applicable to the calculation of the athermal (zero temperature, no zero point energy) equation of state of metals including electronic correlation? For ...
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