Great question!

Yes we can usually determine if a calculation will be expensive by assessing a number of parameters ⬇️
In the context of QM calculations we have to assess whether the level of theory we are using is appropriate. Perhaps we could use a cheaper ab initio, semi-empirical, or DFT method. The choice depends on the question and system!

Also: basis sets
Without going into too much detail, basis sets help to describe the shape and behaviour of electrons around certain atoms. We can make them really detailed (i.e. model every electron) or just model the important ones (ones involved in bonding etc)

en.wikipedia.org/wiki/Basis_set…
Often, people will run benchmark calculations using combinations of different levels of theory and basis set to determine what is best for their question / system.
Jumping to MD: if our system is too large it'll take a very long time to finish. Fortunately we have some tricks to try and speed things up.

There's other issues, for example the protein might not adopt a certain shape during the simulation (and we really need to see it!)
We do have ways to help, these include things like "pushing" our system into a state we are interested in, using a very large and / or a lot of computers, and tweaking some of the parameters in the system to shave off time.

I'll go into more detail about these points this week!

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More from @realscientists

13 Apr
Ok so I had a rather hectic evening, but now let's talk about simulating proteins!
First of all, what's a protein?

Protein's are large biological molecules that are responsible for a myriad of different processes in living things. Feel hungry? In pain? Taste something sweet? Feeling an emotion? All of these things are controlled by a vast array of proteins!
Proteins are amazing! Each one is highly specialised to carry out a specific task, what's incredible is that all proteins are made from the same building blocks called amino acids (AAs).

en.wikipedia.org/wiki/Amino_acid
Read 19 tweets
13 Apr
This is one thing I didn't mention in my MD thread yesterday: solvent models 🧵
What's a solvent model? Simply, it's a way we can model processes that take place in solution (we'll use water as an example since it's the most common)
Proteins (large biological molecules) are usually surrounded by water so it's really important that we model these interactions correctly.

(We'll talk a bit more about proteins today)
Read 10 tweets
12 Apr
Now that we've (hopefully) recovered from our quick tour of quantum mechanics we'll now look at molecular dynamics (MD) 🧵
At the end of my last thread I mentioned that we often use QM methods when we want high accuracy, but these methods tend to get very computationally expensive as our system size increases.

When studying larger systems the exact QM description of a molecule often isn't necessary and how its dynamics evolve over longer time frames becomes a more relevant.

(this may not always be the case!)
Read 19 tweets
12 Apr
So, what is computational chemistry?! The field itself is a subfield of chemistry, incorporating aspects of theoretical chemistry / physics and computer simulations. This allows us as scientists to accurately describe (and predict) the properties of atoms and molecules.
Computational chemistry is broad and draws on many areas of science, notably quantum mechanics (QM), classical mechanics, and thermodynamics. We often draw (both directly and indirectly) on all three of these areas to answer a specific scientific question.
For example, let's say we want to describe the breaking of chemical bonds in a molecule during a chemical reaction. Here it is appropriate to use QM to accurately describe the energies involved with the exchange of electrons.

In this thread we'll dive into QM!
Read 27 tweets
11 Apr
Hi everyone! I'm Will, a computational chemist working in the @choderalab. I'm looking forward to curating this account for the next week, introducing you all to my research, and answering any questions you may have along the way! 🧵
I'm currently based in the UK and (if things go to plan) flying to NYC soon to join the lab after working remotely for the last year(!).

Here's how I'm planning on tweeting this week (but this certainly isn't set in stone) ⬇️
I'll give you an introduction to my field and what areas I work in. We'll cover the broader topic of computational chemistry, some theory, and how we can apply it to biological systems 🧬
Read 7 tweets
30 Mar
So let's talk about sensory perception!

Basic sensory perception involves our 5 senses:
1. Smell
2. Sight
3. Touch
4. Taste
5. Hearing
You may say that all those don't influence how I perceive food but they do!

We know that smell & taste are influential but how do the others come in?

Touch can be done by our hands if we pick up food but it also accounts for how we perceive texture in our mouth!
But touch is super important in the way we experience food, this is why small children will like to pick up and poke unfamiliar or strange-looking food before they will put it in their mouth!
Read 22 tweets

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