Screening atomic estimate

Correlation energy differences (ion), 4f excitation energies A (4f ion) calculated for ionized (unscreened) final states, and screening energy estimates d,(band) and d,(atom). The initial states are the ground metallic configurations. All energies in eV. 

C08-0003. The outer layers of the sun contain He atoms in various excited states. One excited state contains one 1 S electron and one 3 p electron. Based on the effectiveness of screening, estimate the ionization energy of the 3 p electron In this excited atom. 

The effective atomic number is considered to be the difference between the actual atomic number, Z, and a screening constant, S, which is estimated by the use of Slater s rules. These represent an approximate method of calculating the value of S, leading to an estimate of the effective atomic number, ZelT, given by Z - S. The value of S is obtained from the following rules. 

To estimate the broadening of spot size by the thermal velocity of the ions, let us assume that the image gas atoms immediately before ionization have a Maxwell-Boltzmann velocity distribution with an effective temperature T which is very close to the tip temperature Tt. If n(y) dy represents the number of ions arriving at the screen between y and y + dy, we have... 

Our problem is to estimate A . It is the mean repulsive energy of a pair of charges at a distance or1 from each other. This will depend on the effective dielectric constant of the electron gas. This should be large for weak Anderson localization and will effectively screen out the repulsion, except when both electrons are in the same atom. We therefore write... 

The GB model is a modification of the Coulomb equation to include the Born radius of the particle or atom which estimates the degree of the particle s burial within the molecule. Equation 5 relates AGdec to the solvent/solute dielectric (e), the separation between the partial atomic charges r, the effective Born radii R(i and /), and the smoothing function fGR. A Debye-Hiickel screening parameter (k) similar to that used in the PB equation is used to account for the monovalent ions. 

---