Questions tagged [basis-set]
A set of (basis) functions make up a basis set. These functions (generally) represent atomic orbitals whose linear combinations are used to make molecular orbitals (LCAO-MO) in computational chemistry.
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Effective Core Potentials and their "corresponding Pople" basis set
Reading through a handout from Yale shows the author correlating the ECP with Pople basis sets. The author of this says the corresponding basis set for SDD is 6-31G, Def2TZV as 6-311G, LANL2MB as STO-...
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Are the np orbitals of light group 2 elements considered as valence electrons in basis sets?
An old mail archive says that, in the usually used basis sets, polarisation functions are treated by a single-Gaussian treatment even for valence double-zeta basis sets.
A priori, I've done a few NBO ...
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Are diffuse functions necessary for modeling unbound conjugated anions?
According to this paper, and contrary to popular belief, diffuse functions are far from being necessary for the calculation of the electron affinities of the polycyclic aromatic hydrocarbon(PAH)s, due ...
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How to increase basis set while running cluster calculations
I am running (opt+freq)DFT calculations using 6-311G(d) basis set on polymers with different number of monomer units. Upto 2 monomer units optimization is converged but for 4 units max displacement ...
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If you are doing an ONIOM calculation in Gaussian, how do you add both custom MM parameters and a custom basis set using GEN and Amber=SoftFirst?
I am trying to calculate a biological system using AMBER forcefields as my low-layer in ONIOM3. I also want to use a non-native basis set (aug-pc-1 for opt+freq, aug-pc-2 for SPE) that requires custom ...
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Why are Slater-type orbitals used for atomic calculations instead of hydrogen-like orbitals?
Originally, Hartree–Fock atomic calculations were done by using numerical methods
to solve the Hartree–Fock equations, and the resulting orbitals were
given as tables of the radial functions for ...
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How does the electronic structure Hamiltonian scales with basis sets and the number electrons?
Given a chemical system with $N$ electrons and a basis set $S = \{\phi_i\}$ with $K$ basis functions. If one to discretize the Hamiltonian with this basis sets, what is the dimension?
The electronic ...
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How to carry out basis set fitting and extrapolation
I am playing around with basis set extrapolations, and i would like to perform some simple tests by doing some parameter fitting and checking the errors.
The functional form of the fitted curve is ...
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ORCA: meaning of numbers in ORCA.out of MOLECULAR ORBITALS for STO-3G Lithium
For Lithium STO-3G basis set
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How can I get analytical form of GTO primitives for a atom?
As I know, for Hydrogen atom a $1s$ Slater Type Orbital (STO) equation is (I can get it from here):
\begin{equation}\label{STO}
\mathrm{STO} = \sqrt{\frac{\zeta^3}{\pi}} e^{-\zeta r}.
\end{...
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Aluminum Battery with PAC setup : Rapid voltage drop problem after a charge
I am a retired man and seek for activity. I dont have background in chemistry but I want to learn an aluminum battery..the known problem is my aluminum metal get eaten and also corrosion even if using ...
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Effective core potential and Gaussian basis set
Is using the effective core potential (ECP) and Gaussian basis set simultaneously in ab initio calculation a valid approach? For example, is it correct to use ECP for one of the atoms and, instead of ...
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How do you optimize an organo-metalic compound containing cerium in in Gaussian?
I am trying to perform optimisation of the molecule attached. I need to get partial charges and frequencies. The issue is that it doesn't converge with following input:
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Computing energy of Gaussian basis set
I'd like to compute the decay rate using
$$ \Gamma = 2\pi \ | \langle ab|V|cd \rangle|^2 \delta\ (\epsilon_\mathrm{f}-\epsilon_\mathrm{i}), \tag{1}$$
where $a,$ $b,$ $c,$ $d$ are the MOs, $V$ is the ...
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What are the cheapest basis sets able to model intermolecular dipole interactions inside a metal complex and give good relative energies, with DFT?
As a example, If I have a square planar complex of a cation with both a weakly polar ligand (X) and strongly polar ones, like ammonia and water I expect a bit of stabilization due to formation of a ...
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