Benchmarks and Reliable DFT Results for Spin Gaps of Small Ligand Fe(II) Complexes

In two(!) previous posts, I criticized the work of Eunji Sim et al. on the so-called HF-DFT. See here, and here. Guess what, it is finally published after 6 months peer reviewing, see here. So today, I am officially reviewing the paper (my first time, please be gentle!). Disclaimer: this is my personal opinion. The authors, …

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Going to China for a conference! (part 1)

Your email is constantly spammed by predatory conferences and journals? Mine too. And now, it's time for me to strike back. I'm answering a spam email from BIT Life Sciences, which inviting me to their WCAM-2018 conference in Xiamen, China. I suppose the conference is real (see the cover picture), but for sure it is …

My banana is bigger than yours, so it must be better

Finally, I put effort into writing something, not particularly on any calculations that could be published on some high-impact-factor-journals, or any ground-breaking discovery in computational chemistry (such as C2 has 4 bonds). I just read a comedy in the Orca forums and would like to share with you. This is a conversation between two computational …

How many bonds are there in diatomic carbon (C2)?

Question: How many bonds are there in diatomic carbon (C2)? Answer: Who cares? It's a waste of time! Well, in the last ten years, there are debates about the "nature" of C2 chemical bond, leading to a bunch of papers in high-impact journals. A group of people claim that there are four bonds. Some say there are …

Paper review: pancake-bonded p-dimers: dispersion is not enough

A new challenge for DFT: pancake bond. In a nut-shell: The pancake bond is an intermolecular interaction between pi-radicals. Pancake bonding can be considered as a combination of van der Waals interaction and interaction between singly occupied molecular orbitals (SOMOs).   Kertesz et al. very recently showed that it's very difficult to describe the interaction …

Watoc 2017, a negative review

Watoc 2017 is over, and I am exhausted. Tomorrow I have a long-haul flight back to my poor country. The conference is great, with many excellent talks. The organization is "German style": exact and efficient. There are several talks I'm going to discuss in this post, not because they are excellent, but because they raise …

Playing with HF exchange in DFT

Let me get this straight, it's a very bad idea to change the HF exchange in a functional, just in order to fit your expectation or the experimental results. But today, I'm going to do this horrible thing. The reason comes from this Watoc abstract from Burke et al. Basically, the authors claimed that For Fe(II) …

B3LYP* functional

Nowadays, reproducing results from a paper is extremely difficult: There are too many methods, too many software with different implementation. Sometimes we can find "wrong" information from the manual or "experienced" users. Computational details are poorly described, sometimes they are hidden by the authors. Today, I will show you an example with the B3LYP* functional. …

Density functional theory: Wisdom of the crowd – GGA functionals

In the previous post, I used a bunch of LDA functionals to study the hydrogen bond in the water dimer. The idea is quite simple but unique and "novel": combine different exchange and correlation functionals and take an average result. In this post, I update the result with nearly 4000 GGA functionals. Let's discuss A …

Density functional theory: Wisdom of the crowd

Have you ever wondered if it is possible to use many different DFT functionals in your paper, not 5, not 10, or 20? I mean more than 100, or more than 1000? Can we use the results and estimate an average number as well as the standard deviation? In this post, I show that this …