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Polarizable Continuum Model (PCM) in G09 (Part II)
One of the most successful posts this blog has ever published was on certain nuances of the solvation calculations on PCM in G03. However there are some differences in the SCRF modules between G09 and...
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The Gen keyword in Gaussian. Adding an external basis set.
I am frequently asked how to include an extra set of basis functions in a calculation or how to use an entirely external basis set. Sometimes this question also implies the explicit declaration of an...
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Article 7
joaquinbarroso:This is the first time I reblog a post from a fellow computational chemist and the reason why I do it is because of its beautiful simplicity and usefulness. Given the scope this blog has...
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Polarizability and Hyperpolarizability in Gaussian
Calculating both Polarizability and the Hyperpolarizability in Gaussian is actually very easy and straightforward. However, interpreting the results requires a deeper understanding of the underlying...
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The Local Bond Order, LBO (Barroso et al. 2004)
I don’t know why I haven’t written about the Local Bond Order (LBO) before! And a few days ago when I thought about it my immediate reaction was to shy away from it since it would constitute a blatant...
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Delta G of solvation in Gaussian09
How to calculate the Delta G of solvation? This is a question that I get a lot in this blog, so it is about time I wrote a (mini)post on it, and at the same time put an end to this posting drought...
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Natural Bond Orbitals (NBO) Visualization with Chemcraft
It’s been a long time since I last posted something and so many things have happened in our research group! I should catch up with them in short but times have just been quite hectic. I’m glad to...
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Transition State Search (QST2 & QST3) and IRC with Gaussian09
Theoretical evaluation of a reaction mechanism is all about finding the right transition states (TS) but there are no guarantees within the available methods to actually find the one we need. Chemical...
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Elements4D – Exploring Chemistry with Augmented Reality
joaquinbarroso:A bit outside the scope of this blog (maybe), but just too cool to overlook. Augmented reality in chemistry education. Originally posted on : This is a guest post from Samantha Morra of...
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Atoms in Molecules (QTAIM) – Flash lesson
As far as population analysis methods goes, the Quantum Theory of Atoms in Molecules (QTAIM) a.k.a Atoms in Molecules (AIM) has become a popular option for defining atomic properties in molecular...
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Comparing the Relative Stability of Non-Equivalent Molecules
How do you compare the stability of two or more compounds which differ in some central atom(s)? If you simply calculate the energy of both compounds you get a misleading answer since the number of...
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A personal artistic impression of the CompChem Landscape
In a nutshell, computational chemistry models are about depicting, reproducing and predicting the electronic-based molecular reality. I had this conversation with my students last week and at some...
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Quantifying σ-Holes – G09 and MultiWFN
Some atomic properties such as an atomic charge are isotropic, but every now and then some derivations of them become anisotropic, for example the plotting of the Molecular Electrostatic Potential...
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The ‘art’ of finding Transition States Part 1
Guillermo Caballero, a graduate student from this lab, has written this two-part post on the nuances to be considered when searching for transition states in the theoretical assessment of reaction...
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The “art” of finding Transition States Part 2
Last week we posted some insights on finding Transitions States in Gaussian 09 in order to evaluate a given reaction mechanism. A stepwise methodology is tried to achieve and this time we’ll wrap the...
View ArticleNo, seriously, why can’t orbitals be observed?
The concept of electronic orbital has become such a useful and engraved tool in understanding chemical structure and reactivity that it has almost become one of those things whose original meaning has...
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All you wanted to know about Hybrid Orbitals…
… but were afraid to ask or How I learned to stop worrying and not caring that much about hybridization. The math behind orbital hybridization is fairly simple as I’ll try to show below, but first let...
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Post Calculation Addition of Empirical Dispersion – Fixing interaction energies
Calculation of interaction energies is one of those things people are more concerned with and is also something mostly done wrong. The so called ‘gold standard‘ according to Pavel Hobza for calculating...
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DFT Estimation of pKb Values – New Paper in JCIM
As a continuation of our previous work on estimating pKa values from DFT calculations for carboxylic acids, we now present the complementary pKb values for amino groups by the same method, and the...
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Natural Transition Orbitals (NTOs) Gaussian
The canonical molecular orbital depiction of an electronic transition is often a messy business in terms of a ‘chemical‘ interpretation of ‘which electrons‘ go from ‘which occupied orbitals‘ to ‘which...
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