Questions tagged [basis-sets]
For questions about the usage and construction of electronic structure basis sets.
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How to interpret molden AO/MO coefficients?
A simple calculation with Molpro 2012 on H2 molecule in cc-pvtz basis produces a molden file with 28 molecular orbitals. Each MO is defined with 30 AO/MO coefficient, but the number of symmetric AOs ...
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What are the advantages of plane wave basis? [duplicate]
For systems with periodic boundary condition , plane wave basis is usually adopted. While for molecular systems, gaussian basis set is normally adopted. For periodic systems, the gaussian basis is ...
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Predicting linear dependencies in a basis set in advance of calculating any integrals
I've been doing some calculations for a water molecule, with a big uncontracted basis set: For oxygen I am using aug-cc-pV9Z supplemented with the "tight" functions from cc-pCV7Z. The s-type exponents ...
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Avoiding charge-migration in electronic structure calculations with solvent-like environments
When performing electronic structure calculations on a molecule, one can surround it with point charges to mimic a solvent environment, and lend polarization effects. There is a bit of a caveat ...
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Which basis set families were optimized to give the lowest possible variational energy for a given number of orbitals?
Dunning's basis set families (such as cc-pVXZ and aug-cc-pCVXZ) were not optimized to give the lowest variational energy for a given number of orbitals. For example the S-type orbitals are optimized, ...
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Understanding the difference between Dunning and Karlsruhe basis sets
I have heard that TURBOMOLE works extremely fast (even compared to MOLPRO) with def2 basis sets, but is slow if Dunning basis sets are used.
What is it about def2 basis sets that allows calculations ...
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What functions other than Gaussians are used for orbital basis sets?
The Gaussian function $\propto\exp((x-a)^2/b)$ with $b>0$ is one of the most common functions used in molecular modelling (e.g. Gaussian type orbitals).
What are some examples of applications of ...
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What are good basis sets and functionals for Ni, Cd and Pb?
I will setup a single point energy calculation using Gaussian for a system containing atoms of B-N-Ni, B-N-Pb and B-N-Cd.
The system are slabs of boron-nitride [1,2] interacting with those metals.
...
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What are the scientific justifications of the binding energy equation?
There are many problems where we want to calculate the binding energy between two systems.
Normally, we have a system A, adsorbent (a surface, a nanotube, a protein, etc.), that interact with a system ...
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Functionals/basis sets optimized with respect to properties?
In general (at least for molecular calculations) basis sets and DFT functionals are fit to some high level calculation or experimental energy. It is speculated that an accurate energy will result in ...
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Approximate equivalence table between Pople's basis sets and Jensen's DFT optimized polarization consistent basis sets (pcseg-n)
At first I posted this question in chemistry.stackexchange.com, before materials.stackexchange.com was launched in beta. As it went unaswered, I'm giving a try here.
I have some calculations results ...
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What are the positives and negatives of periodic DFT codes that don't use plane-wave basis sets?
Most periodic density functional theory (DFT) codes use plane-wave basis sets in conjunction with three-dimensional periodic boundary conditions. In contrast, for molecular systems of finite size, ...
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What methods can be used to calculate excited-states in molecular crystals?
In periodic systems plane-wave basis functions are often used. In a previous question on this site it was questioned if plane-wave basis-sets are reliable for modeling adsorption-processes
The ...
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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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How trustworthy is the Tran-Blaha modified Becke-Johnson potential and how does it perform across basis sets?
When modeling solid-state materials and particularly semiconductors, one must go beyond LDA and GGA. One alternative is to use hybrid functionals or the $GW$ method. However, this can be very ...
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Are plane-wave basis sets reliable for modeling adsorption processes?
Plane-wave basis sets are useful in the calculation of periodic systems and can be used in combination with pseudopotentials. However, when dealing with surfaces the system is no longer periodic in, ...
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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 ...
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Why were no correlation consistent basis sets for potassium contracted for a non-relativistic Hamiltonian?
On basis set exchange, the only correlation consistent (cc) basis sets for potassium, are relativistic (labelled by X2C). Very recently (I consider 2017 quite recent, because most Dunning basis sets ...
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