Absorption and Emission Spectra with Gaussian 16 In photosynthesis research, emission spectra—particularly chlorophyll fluorescence—are not merely complementary to absorption measurements but are often more informative. While absorption spectra i…

In photo physics (as in photosynthesis) calculating emission spectra is as-if not more-important as calculating absorption. A new guest blog post on how to do it in Gaussian 16 by @gustavmondragon #CompChem #TDDFT #EmissionSpectra #Spectroscopy

joaquinbarroso.com/2026/03/30/a...

Absorption and Emission Spectra with Gaussian 16 In photosynthesis research, emission spectra—particularly chlorophyll fluorescence—are not merely complementary to absorption measurements but are often more informative. While absorption spectra indicate which wavelengths are harvested, emission spectra reveal the fate of that energy, providing direct insight into its partitioning between photochemistry, heat dissipation, and fluorescence. In this way, they serve as sensitive probes of energy transfer efficiency among pigments and of the functional state of the photosystems.

Calculating emission spectra with Gaussian16

Can Frustrated Lewis Pairs Really Split Water? A New Paper in Inorg. Chem.

Obtaining hydrogen from water is one of those topics that attracts lots of attention from many fronts in chemistry; on paper, it can be clean, elegant, and deceptively simple. In practice, however, water is stubborn and…

One electron C-C bond or Weak Interaction? New paper in PCCP The compound spiro-dibenzocycloheptatriene (figure 1) made headlines a year ago by claiming that the ipso carbon atoms across the molecule were bound together by a single electron σ bond. This is truly a seductive idea: that somewhere out there, in the shadows of open-shell aromatics, carbon atoms might form a single-electron σ-bond — a unicorn of bonding, indeed. Since bold claims require bold scrutiny, we went ahead and dissected the electronic structure of the radical molecule in question with all the tools at our disposal; We also analyzed that of the neutral complex from where it was derived and also the double cation to analyze the consequences of removing the alleged electron holding such an unusual interaction, for if this C-C bond truly exists, it should alter the interaction energy between the fragments in a way consistent with a real σ bond.

One electron C-C bond or Weak Interaction? New paper in PCCP

The compound spiro-dibenzocycloheptatriene (figure 1) made headlines a year ago by claiming that the ipso carbon atoms across the molecule were bound together by a single electron σ bond. This is truly a seductive idea: that somewhere…

That’s so nice! Thank you!

I've been struggling with some calculations for a couple of days now only to find the solution in my own blog *sigh*
Should I be glad I made a sort of note for my future self or should I be concerned about getting older?

/home/myself/manuscript_submitted be like:

manuscript.docx
manuscript_rev1.docx
manuscript_rev1_comments.docx
manuscript_rev2_notracks.docx
manuscript_rev3_1_final.docx
manuscript_refs1_1_final_final_notracks.pdf
re_manuscript_4_2_3_1_referees_final_comments_annotated.docx

Bond Dissociation Energy with Gaussian16 The strength of a chemical bond can be defined as the change in enthalpy when a bond is homolytically broken into two radicals. Bond dissociation energy is thus the measure of the strength of a bond and, while it is temperature dependent, it can be calculated by DFT or ab initio methods. In this tutorial we're going to calculate the C-H bond dissociation energy (BDE) in the methane (CH4) molecule, one of the strongest aliphatic bonds in organic chemistry.

Bond Dissociation Energy with Gaussian16

The strength of a chemical bond can be defined as the change in enthalpy when a bond is homolytically broken into two radicals. Bond dissociation energy is thus the measure of the strength of a bond and, while it is temperature dependent, it can be…

#IYQ2025 Are the 2 electrons in a covalent bond 'entangled'? I mean, in the sense of 'Einstein's spooky action at distance'. If so, what would that imply for a homolytic cleavage? Would both mol fragments be entangled? Is electron correlation somehow related to that entanglement?

The man of MOFs and more Nature Reviews Chemistry - Ahead of his 60th birthday, Omar Yaghi discussed his life in science so far and where he believes is the exciting space for future developments.

Congratulations to this morning's Nobel prize winners. If you'd like to read a little more about one of them - Omar Yaghi - then do check out this recent Q&A we published ahead of his 60th birthday earlier this year. rdcu.be/eJ3vj #ChemNobel2025 #chemsky 🧪

Si thrilled to finally see Prof. Omar Yaghi getting a most deserved Nobel prize!

Chemists west of the Atlantic Ocean: Are you in Alfred Nobel’s Good or Naughty list?
Go to bed now.
#ChemNobel

How appropriate that this Intl. year of the quantum sciences, the Nobel Prize in Physics is awarded to Macroscopic Quantum Tunneling Effect. Paraphrasing Sabina Hossenfelder: "Thanks to this, we can keep discussing the interpretation of Quantum Mechanics, but now inside a clean room." 🧪
#IYQ2025

Fortunately, the news tunneled its way to the recipient.

it's actually not two Nobels for Josephson junctions, just one that tunnelled over a gap of 52 years

Thank you, Ken. That’s a great question, i.e. I don’t have the answer. I guess that the HK theorem requires 3D space to be fundamental, otherwise the external potential could be non unique, unless this potential led to the emergence of it. However we should then be able to extend HK to the subatomic

Is Quantum Chemistry aligned with the Copenhagen or the Many Worlds interpretation of Quantum Mechanics? 2025 was declared by UNESCO as the International Year of Quantum Sciences, bringing a lot of celebrations, however much of the discourse is dominated by physicists and quantum technologists, some of which proclaim the dawn of the new "quantum revolution". Yet, amid the excitement, I can't help but notice that quantum chemistry remains underrepresented, despite being the discipline that has arguably done the most to turn quantum mechanics into a practical, predictive science.

If not thought-provoking, at least I hope it's talk-provoking. A new blog post on Quantum Chemistry and the interpretations of Quantum Mechanics.

This is happening in an hour, join me to talk all things #chemnobel

Unrecognized potential number 6 in GetPot

Unrecognized potential number 6 in GetPot A rather silly error in Gaussian, but one that seems to be common and to which I haven't found any posted solutions, so here goes mine. This error shows up when reading an external basis set and looks like this…

Indeed! Go Cubs!!

#CompChem in the #Postseason be like

Ah! We have a provocateur here!

LOL yes! (Almost) Every. Single. Year.

#ChemNobel season is upon us. Which flavor of chem do you think will be recognized this year?
Comment tour top picks.

Phys/Theo
Org
Inorg
Med/Bio

Julieta Fierro: "La ciencia nos demuestra que no tenemos la verdad" YouTube video by Aprendemos juntos Mex

La pasión por la ciencia nunca le cupo en el pecho. Por eso la derramó sobre todos los que la conocimos. DEP Dra. Julieta Fierro Gossman

Fui invitado a Sensacional de Científicos para hablar sobre el año de las Ciencias Cuánticas
Véanlo completo en YouTube o escúchenlo en su podcasteria favorita
YouTube: youtu.be/2Mul2CMUJLk
Spotify: shorturl.at/fQLZb
Apple Podcasts: shorturl.at/CwKpf

Using DensToolKitViewer to get the best viewpoint In this tutorial, we shall prepare a figure using DensToolKitViewer 2.1.0 (or later) to select the viewing angle of the molecule, for whenever the default view isn't the optimal viewpoint or to get various for comparison. Installation and main controls were already covered in a previous post, as well as an update for ease of use. We use the file…

Using DensToolKitViewer to get the best viewpoint

In this tutorial, we shall prepare a figure using DensToolKitViewer 2.1.0 (or later) to select the viewing angle of the molecule, for whenever the default view isn't the optimal viewpoint or to get various for comparison. Installation and main…

DensToolKit2: A comprehensive open-source package for analyzing the electron density and its derivative scalar and vector fields In this article, we provide details of the suite DensToolKit-v2, which consists of a set of cross-platform, optionally parallelized programs for analyzing the m

Glad to hear that, Marcelo! Here's the link to the original paper. You can go to the blog and collect all posts regarding DensToolKit and subscribe for the upcoming ones!
Share, cite, you know the drill ;-D

pubs.aip.org/aip/jcp/arti...

Installing and uninstallng DensToolKitViewer The new DensToolKitViewer just got even better! So, if you want to update DTKViewer to make the most of the new features, in this tutorial we shall compile and install DensToolKitViewer. We provide the explicit steps to compile under Ubuntu and under MacOSX. We will assume that the git repo is cloned in /home/your_username/Downloads. For this, execute the following commands…

Installing and uninstallng DensToolKitViewer

The new DensToolKitViewer just got even better! So, if you want to update DTKViewer to make the most of the new features, in this tutorial we shall compile and install DensToolKitViewer. We provide the explicit steps to compile under Ubuntu and under…

En cuanto me inviten estoy allá!!