A crystallographer’s concerto

Words by Bill Clegg (in the style of Michael Flanders and Donald Swann’s Ill Wind).

Music by Wolfgang Amadeus Mozart: Horn Concerto number 4 (K495), 3rd movement: https://www.youtube.com/watch?v=VHbLV7G4vno.

Written for the ‘Science Slam’ entertainment session at ECM34, Padova, 2024:

For crystal growth, I had to dissolve it and let it cool.
Upon my oath! It’s incredibly boring to see.
But to my surprise, and in front of my eyes,
A crystal did grow to useful size.
Oh, what a pain of learning to cope
With peering for hours down a microscope!

But that was yesterday, and now today
I looked for diffraction effects.
There were the spots, but they didn’t fit a lattice.
What on earth does it mean?
Single crystals give patterns without a flaw.
Oh, could it be a twin?
Yes indeed! Now I need
Clever software to find me a twin law.

Next integrate
And corrections apply to sigma and I.
Then I can use direct methods in structure solution.
If that doesn’t work, I’ll try flipping the charge
To look for electrons and their distribution –
Molecular fragments that I can enlarge.
Tutti

What a joy! Finding atoms in a Fourier,
Hydrogens showing up in a difference map.
This is easy, I learnt how to do it at Erice
With SHELX, or OLEX, or some other app.
Now everything’s found, the structure is sound.
It’s time to start the tricky part –
The first refinement round.
Now, I urge: please converge!

Away now we go with our least-squares refinement,
Constraining, restraining, and weighting it all.
The model gives data approaching alignment
With measured diffraction; the R factor’s small!
Tutti 

It’s looking fine; the goodness of fit is precisely 1 –
A pleasing sign! Shout out loud: I’m on cloud nine!
Now on the screen the structure is seen,
No more density showing between.

A lovely molecule – it’s really cool!
I’ll show it at ECM.
I’ll devise a surprise
And I’ll snaffle the main poster prize!
I just need a nice diagram
Showing the molecules in the cell
And ellipsoids to prove I am
Not just a fraud.
Cadenza 

And then publication – the very best journal,
Attracting citations all over the place.
My new reputation will blossom eternal,
I’ll enter the database!
Tutti 

I’m getting excited! I should wait till later,
My fingers are flying around.
I’ve just hit DELETE and I’ve lost all my data
And made an unprintable sound! #***!
And now comes the moment I dread,
Those crystals are looking quite dead.
I’ll have to use powder instead!!!
EPDIC*!!

 *European Powder Diffraction Conference