On the structure of Vanadium Deuterides: How computational chemistry can teach us something on Love
So Valentine’s Day (VD) is right around the corner. I am sure many of you are preparing your finest purchases from the flower shop in Aylor. Perhaps you’re preparing to send a trivia point sampler package, akin to the commonly purchased chocolate assortment. However, what is the best way to show your intentions and feelings to others? Are more complex expressions of love most important on Valentine’s Day? I suppose at this point has been eternally debated, with many wizened individuals answering these questions.
Let us approach the question of “What is the best approach to displaying your intentions to your valentine?” from a non-intuitive angle: What can computational chemistry teach us about love?
Taking a chemists approach to this, VD will be vanadium deuteride ionic complex. Vanadium is a transition metal often used to produce alloys, most commonly found in jet engines, and often found in certain grades of steel. Deuteride is the anionic form of deuterium, which is an isotope of hydrogen. Chemically speaking deuterium and hydrogen are essentially equal in reactivity, however there are notable differences in weight between the two, which can lead to interesting studies and applications. Most commonly, deuterium is found in “heavy” water, which is water used to control nuclear reactors.
Two different ionic compounds, VD3 and VD5, were analyzed using molecular mechanical (MM) and density functional theory (DFT). Essentially, MM and DFT are complex mathematical equations that can be solved (mercifully by a computer) to predict how electrons interact with each other. Once we can predict how the electrons behave, we can predict where the atoms are. Once we know where the atoms are, we know the shape of the molecule (VD3 or VD5, in this case), and shape can tell us a great deal of information.
MM and DFT are different in that DFT is a far more complex mathematical equation, where it takes several times longer for the computer to finish calculating as compared to MM which takes seconds, at worst. Concomitantly, it should be stated that DFT offers a better predictor of what the molecule looks like as compared to MM which can be thought of as a ‘very Take your time (DFT) and it will go noticed.good guess.’ Remember, anything worth doing will take some time.
So what does this tell us about love and life?
Let us examine the two answers we get from VD3 with MM and DFT ‘answers’ calculated for both of them. We will compare two things: shape and distance between atoms. With regards to the MM optimized structure, the three V-D distances are 1.54079 Ȧ, 1.53968 Ȧ, 1.53924 Ȧ respectively and took 2 seconds to complete the calculation. These are essentially the same distances, within error. The DFT structure had distances of 1.69048 Ȧ, 1.68837 Ȧ, 1.68876 Ȧ, which, while different from the MM structure, are essentially the same with respect to each other. The calculation took approximately 6 hours to complete. Despite the difference in V-D distances, the overall structure of the molecule looks the same, forming the expected trigonal planar molecule possessing D3H symmetry (See Figure 1 and Figure 2).
With respect to the VD5 molecule the MM structure and the DFT structure followed the trends seen in the VD3 structure, with the MM structure having shorter bond distances than the DFT but there is a difference in the overall structure. The DFT produces a distorted square pyramidal structure with C4V symmetry, while the MM produces the expected trigonal bipyramidal structure with D3H symmetry (See figure 3 and figure 4). It is unclear which structure is the more correct structure. Perhaps both can exist, with one being more stable than the other. The second difference between the MM and DFT structure for VD5 came from the time, where MM took about 2 seconds and the DFT took well over 10 hours to complete.
Time aside, what does this mean? DFT gives more accurate responses, as most metal – hydride distances are large, being around 1.6 – 1.8 Ȧ. The structure looks the same, at first glance, but when you examine the small details, you will notice the extra time spent to make the best effort.
This leaves us with the following conclusion: when approaching VD (Valentine’s Day) effort does count. Take your time (DFT) and it will go noticed. It may take significantly longer (2 seconds vs 10hours) but at the end it will be worth it.
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