# Tag Info

Accepted

### Advice on converging a restricted open-shell DFT (rob3lyp/LANL2DZ) single point Gaussian09 calculation for a triplet spin-state molecule?

Before introducing solutions to solve this problem, let us analyze unnecessary keywords: pop=full IOp(3/33=1) use=L506 does not affect the SCF convergence at all, ...
• 806
Accepted

### At what point in the Hartree-Fock formalism is the Fock operator introduced?

Your steps 1 and 2 are unnecessary. The single determinant variant of Hartree-Fock is simply derived by assuming that the wave function is a single Slater determinant; after all, this is the simplest ...
• 19.7k

### Why do we specifically need an SCF-generated charge density for calculating the density of states (DOS) and band structure?

Background At the heart of a conventional DFT simulation are the Kohn-Sham equations, $$\left(-\frac{\hbar^2}{2m}\nabla^2 + \hat{V}\left[\rho\right]\right)\psi_{bk} = E_{bk}\psi_{bk} \tag{1}$$ where ...
• 8,132
Accepted

### How do I get the energy, if I have the wavefunction?

"For a known wave function, should I not be able to determine the energy?" The wavefuncton is an eigenfunction of the Hamiltonian, and the energy is a corresponding eigenvalue of the same ...

### Using Hindered Rotor Scans With Different Convergence Criteria from Gaussian

Thatâ€™s a bit up to interpretationâ€¦ I guess it depends on what you want to get out of the scans exactly (i.e., are the geometries important, or just the energies on those geometries?). If you want the ...

### How do I get the energy, if I have the wavefunction?

UPDATE: I didnt read your post carefully enough. My answer is irrelevant. In your comment above you said I guess what i meant was that if I have an arbitrary state eigenfunction (approximated as the ...
• 1,563

### SCF calculations for new materials with unknown properties (e.g. charge, spin, magnetization) using Quantum Espresso

To determine if any material has "spin, total magnetization, net charge or if they are metallic", some steps can be done in order to check if they are/or not. First it should be safe to ...
• 1,522

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