# Questions tagged [ab-initio-calculations]

For questions about ab-initio (first principle) calculations.

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### Are nuclear ab-initio methods related to materials ab-initio methods?

I just read this synopsis in Physics where scientists used first-principles nuclear physics calculations to predict the stability of 700 isotopes up to iron. I didn't know that this was possible, ...
209 views

### DFT Knowledge Check for Posed Problem

Currently I am trying to apply to a graduate program overseas. They require me to include a research proposal in my application. This doesn't make much sense to me since how can I write a research ...
364 views

### What is the procedure for constructing an ab initio potential energy surface for CH3Cl + Ar?

I would like to construct a model analytical potential function for collision between CH3Cl and Ar. This would be the sum of CH3Cl intramolecular + CH3Cl---Ar intermolecular potential. First I would ...
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### What's the physics contained in the exchange-correlation functional in the framework of KS-DFT?

This question is inspired by this post. In the Kohn-Sham framework of density functional theory, the total energy is expressed as: $$E=E_{kin}^{non}+E_{ext}+E_{H}+E_{xc}$$ in which The first term is ...
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### Floquet's Theorem and ab-initio Calculations

Are there any ab initio packages that take advantage of Floquet's theorem (which one can think of as a generalization of Bloch's theorem from space to time) in order to study the impact of an ...
32 views

### Rotational magnetic moment and ab-initio calculations

Rotating molecules have an associated magnetic moment that can couple with both nuclear and electronic spin magnetic moments, thereby impacting the hyperfine energies of rotating molecules. Can one ...
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### Signatures of Competing Orders in Ab Initio Calculations

Some materials have various competing and/or synergistic orders, such as charge density waves and superconducting pairing. Are there signatures of such an interplay between orders that can be seen in ...
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### ab-initio calculations beyond s-wave BCS superconductors

Conventional superconductors are often modelled using Bardeen-Cooper-Schrieffer (BCS) theory with an s-wave order parameter, but not all superconductors describable with BCS theory have an s-wave ...
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### How are pseudogap phases typically modelled?

Cuprate superconductors have a pseudogap phase that is not well-understood. What attempts have been made to understand the pseudogap phase from an ab-initio perspective?
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### Calculating the band structure with different unit cell

I have to do a electronic band structure calculation on a heterostructure using DFT calculation. First I do the calculation on each phase separately. I use a primitive unit cell to do the calculation ...
125 views

### AIMD and velocity scaling in VASP

Typically one does velocity scaling to "heat" their sample with MD. How do we do this in VASP? Is it by setting the SMASS=-1 and ...
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### Which properties of a material calculated using density functional theory are affected by smearing?

Smearing (smearing width $\sigma$, to be precise) has always been confusing. I understand what it is but can't pin it down when it comes to DFT calculations. Should it be converged like k-points and ...
149 views

### Permissible amount of forces on ions in a relaxed structure

An equilibrium structure would be at a local minimum but that doesn't happen with all relaxation calculations. Relaxed structures tend to have some resultant forces on ions. What amount of these ...
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### When using the “even tempered method” for augmenting basis sets, what justification is there for the numerical factor which is used?

Diffuse functions are often added to basis sets using "even-tempered" exponents, or sometimes I have heard the phrase "even tempering". In this paper by Jacek Koput, the author says "the customary ...