van der waal


Lennard-Jones Potential

The Lennard-Jones model consists of two ‘parts’; a steep repulsive term, and smoother attractive term, representing the London dispersion forces. Apart from being an important model in itself, the Lennard-Jones potential frequently forms one of ‘building blocks’ of many force fields. It is worth mentioning that the 12-6 Lennard-Jones model is not the most faithful representation of the potential energy surface, but rather its use is widespread due to its computational expediency.The Lennard-Jones Potential is given by the following equation:


  • V is the intermolecular potential between the two atoms or molecules.
  • ϵ is the well depth and a measure of how strongly the two particles attract each other.
  • σ is the distance at which the intermolecular potential between the two particles is zero (See Figure 1.2). σ gives a measurement of how close two nonbonding particles can get and is thus referred to as the van der Waals radius. It is equal to one-half of the internuclear distance between nonbonding particles. 
  • r is the distance of separation between both particles (measured from the center of one particle to the center of the other particle).
  • Minimum value of Φ12® at r=rmin

The stability of an arrangement of atoms is a function of the Lennard-Jones separation distance. As the separation distance decreases below equilibrium, the potential energy becomes increasingly positive (indicating a repulsive force). Such a large potential energy is energetically unfavorable, as it indicates an overlapping of atomic orbitals.  However, at long separation distances, the potential energy is negative and approaches zero as the separation distance increases to infinity (indicating an attractive force). This indicates that at long-range distances, the pair of atoms or molecules experiences a small stabilizing force. Lastly, as the separation between the two particles reaches a distance slightly greater than σ, the potential energy reaches a minimum value (indicating zero force).  At this point, the pair of particles is most stable and will remain in that orientation until an external force is exerted upon it. 

This gives rise to Bond Dissociation energy 

Tokay Gecko foot …

The key to the gecko’s sticking success lies in tiny hairlike structures, called setae, found on the base of its toes. Each of these microscopic bristles can split into hundreds of nano-sized tips called septulae. Septulae create so-called van der Waals interactions between their molecules and the molecules of the surface that a lizard is clinging to. Such interactions are normally weak, but because there are millions of septulae on each of a gecko’s toes, each tiny bristle adds a small grip, which together creates a secure hold. A million setae, which would fit neatly on a dime, could support the weight of a child.

#gecko #foot #amazing #animal #animals #reptile #lizard #science #wild #wildlife #wildlifephotography #indonesia #tokay #macro #nikon #detail #d800 #shannonwild

6x09 “A” Reveal

So I think this ending already gave a lot away… but you could interpret it 3 ways. I am not sure that this is Charles revealing himself to Alison. Look at her face and I think the “It’s you” in the 6x09 promo is from that exact moment as well… Alison is not shocked. She’s suprised but not shocked like facing her long lost brother, supposely someone she’s never met at this age. But there are 3 ways to look at it:

a) This is Mona revealing herself to Alison as either A’s little helper or they have been working together secretly (this is what I think!) and she’s on the A hunt too, thinks it’s too dangerous for them or has a good guess she’s about to tell her (this adds up with what we see in the 6x10 promo) and would explain the height difference when A kidnapped her. Alison also looks very disappointed. So this could be because she has expected to meet her brother and now it’s just Mona. Plus the “It’s you” sounds pretty neutral, not like some great revelation. Anyhow it would not make sense for her to take Ali to Radley and show the girl the way in. But on the other hand we do not see her in the Radley..

b) Cece revealing herself as Red Coat / A. I think it’s an option but not very likely to happen because we get a seperate scene for the Red Coat reveal next episode and it’s somewhere in the woods… Also I think Alison would be far more than disappointed, she’d be furious if A reveals itself as Cece so that is not the reaction we’d see.

c) If this is indeed Charles revealing himself to his sister, what would make sense because he takes her to Radley in the promo - on one condition: Alison has seen his face before and right in that moment everything is adding up in her mind. This could be Wren even tho we have not seen them together on screen.. but she has been watching (over) the liars as well. She must’ve seen or even encountered him at one moment [Wren or not]. I hope this is true and we get a flashback. He could’ve been helping her hide or get entry to Radley and stuff when she was still hiding out..