Questions tagged [density-functional-theory]
Density functional theory (DFT) is a quantum mechanical model used to estimate the electronic structure of molecules and condensed matter. In broad terms, DFT works by treating all the electrons in the system as a single electron density, and computing physical quantities of interest as functionals of that electron density. (from Physics.SE)
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Second derivative terms of DFT functional
Given the density functional to KSF matrix elements
$E^{XC} = \int dr f(r,R)$,
where $r$ and $R$ denotes electronic and nuclear coordinates, respectively.
Suppose we have an LDA functional, which can ...
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How to interpret molecular orbital (HOMO - LUMO) plots in Chem3D 22.0?
Recently, I have been trying to understand the origin of the difference in reactivity of alkynyl-boron(ate) complexes so I tried to generate a molecular orbital plot on Chem3D (Version 22.0.22 64bit) ...
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Comparing calculated DOS with experimental valence band spectra for oxidized platinum nanoparticles
I've been studying the electronic structure of platinum nanoparticles using DFT and have a question about comparing my calculated density of states (DOS) with experimental valence band spectra.
I ...
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How to rotate Octahdrals locally along with unit cell axis
I am curious about crystal field effects on a given atom by analysing $m_l$
projected DOS, the individual d-orbitals are given with respect to the Cartesian coordinates (not the lattice constants). So ...
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How to find the global minima of a supramolecular complex in computational chemistry?
So this is more of a complex problem, and my masters thesis could greatly benefit if I find an answer to this.
Essentially, I have a supramolecular inclusion complex. There is this molecule A (the ...
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Define a rate-determining step and an energy barrier for a multi-step reaction profile
I am currently making reaction profile by means of DFT calculations. I am able to correctly draw a whole reaction profile.
However, I am struggling to find what exactly is the energy barrier of a ...
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N2 HOMO-LUMO Gap calculation
I am thinking about calculating the HOMO-LUMO energy gap for $\ce{N2}$ molecule.
I thought I could model this as a particle in a box problem to find $E_\text{HOMO}$ and $E_\text{LUMO}$.
The formula I ...
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Can we use DFT to compute the potential energy of dynamic processes?
Suppose we want to determine the potential energy between a hydrogen atom and a surface, such as Cu(001), during hydrogen scattering on Cu(001) surface, assuming that the hydrogen atom does not change ...
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Energy Decomposition Analysis for SN2 involving ambident nucleophiles and an alkali metal counterion
I am wanting to perform an EDA on transition state structure of the nucleophilic attack of an ambident nucleophile (2 atoms that could be used in nucleophilic attack on the same molecule) on a benzyl ...
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Can geometry of a molecule change when the spin-orbit coupling is taken into account? [closed]
Cross-posted on MMSE.
Is there any evidence that spin-orbit coupling (SOC) leads to significant changes in atomic structure? Using DFT, I am getting different relaxed lattice constants when I take SOC ...
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Gaussian16 optical rotation calculation using a deuterated species
I am running into issues preparing an input file for DFT calculations. Currently, I am trying to submit an optical rotation calculation for an alpha-deuterated benzyl bromide (1 deuterium on the ...
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Behavior of the Vosco-Wilk-Nusair correlation functional
Assumptions:
interacting system
uniform gas system
In the Kohn-Sham model, the exchange correlation functional is introduced to account for correlation energy $\epsilon_{xc} = \epsilon_{x} + \...
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What is the difference between zero-point and total energy of a molecule in the output of an ORCA FREQ calculation?
I am trying to find the enthalpies of formation for a couple organometallics in ORCA and as a first time user I am a bit bogged down in the terminology. The Gaussian manual has a section on these ...
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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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How can I calculate the electrostatic energy between two fragments?
I have a 2-fragment molecular complex with partial charge transfer from fragment 1 to fragment 2. The binding energy is ~0.3 eV and I want to evaluate what fraction comes from electrostatic attraction....
