CCL: HOMO energy and redox potential

Hi Muhammad,
 Unless there is some underlying physical reason that allows one to derive
 the the relationship you proposed, I think it's just a mathematical fit. If
 you change the exponent on r, from say 2 to 6, you'll still get
 "reasonable" linear fits for IP ~ log(-k). For example, here's r^3:
 > k3 = V/(m*(r^3))
 > pro <- lm(IP ~ log(-k3))
 > summary(pro)
 Call:
 lm(formula = IP ~ log(-k3))
 Residuals:
       1       2       3       4       5
 -11.023  27.474 -15.087   2.521  -3.885
 Coefficients:
              Estimate Std. Error t value Pr(>|t|)
 (Intercept) -1892.162    377.784  -5.009  0.01532 *
 log(-k3)       32.791      5.304   6.182  0.00852 **
 ---
 Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01
 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
 Residual standard error: 19.37 on 3 degrees of freedom
 Multiple R-squared:  0.9272, Adjusted R-squared:  0.903
 F-statistic: 38.22 on 1 and 3 DF,  p-value: 0.008523
 Best,
 Adam
 On Mon, Aug 29, 2016 at 10:24 AM Muhammad Abduh Nasution abduh^
 mhs.unimed.ac.id <owner-chemistry(~)ccl.net> wrote:
 >
 > Sent to CCL by: "Muhammad Abduh Nasution"
 [abduh]~[mhs.unimed.ac.id]
 > Dear CCL members.
 > First, forgive me if this
 > discussion may be not too
 > computational chemistry. I've
 > read many literature states that
 > there are relationship between
 > HOMO energy and redox
 > potential, even this topic can be
 > found on CCL archive. So I try to
 > relate them based on data from
 > "Oxtoby, D. W. (2008).
 > Principles of Modern
 > Chemistry" and "Lide, David R.
 > (ed). (2005). CRC Handbook of
 > Chemistry and Physics". I found
 > that Ionization Potential of
 > alkali metal and logaritmic
 > function from \frac{V}{Mr\times
 > r^5}\ (where V is redox potential
 > in Volt, Mr is relative mass of
 > atom in kg, and r is atomic radii
 > in m), is have strong correlation
 > showed by its R-squared. Here
 > is script written in R, altough
 > basically I'm python
 > programmer.
 > # data sequences of alkali
 > metal properties
 > > element<-
 > c('Li','Na','K','Rb','Cs')
 > # Ionization Potential of alkali
 > metal
 > > IP<-
 > c(520.2,495.8,418.8,403,375.7)
 > # redox potential of alkali metal
 > > V<- c(-3.0401, -2.71, -2.931, -
 > 2.98, -3.026)
 > # defining Angstrom unit
 > > A = 10^-10
 > # atomic radii of alkali metal
 > > r<- c(1.52*A, 1.86*A, 2.27*A,
 > 2.47*A, 2.65*A)
 > # atomic relative mass of alkali
 > metal in kg
 > > m<- c(0.0069412,
 > 0.02298977, 0.03909831,
 > 0.08546783, 0.132905452)
 > # defining k
 > > k = V/(m*(r^5))
 > # relating between k and
 > ionization potential
 > > data <- data.frame(x=log(-k),
 > y=IP)
 > > pro <- lm(y ~ x, data=data)
 > > summary(pro)
 > Call: lm(formula = y ~ x, data =
 > data) Residuals: 1 2 3 4 5 -
 > 10.883 25.245 -13.378 2.646 -
 > 3.629 Coefficients: Estimate
 > Std. Error t value Pr(>|t|)
 > (Intercept) -14167.3 2164.1 -
 > 6.547 0.00725 ** x 3074.9
 > 455.5 6.751 0.00664 ** ---
 > Signif. codes: 0 '***' 0.001 '**'
 > 0.01 '*' 0.05 '.' 0.1 ' ' 1 Residual
 > standard error: 17.84 on 3
 > degrees of freedom Multiple R-
 > Squared: 0.9382, Adjusted R-
 > squared: 0.9177 F-statistic:
 > 45.58 on 1 and 3 DF, p-value:
 > 0.006638
 > > data.entry(data)
 > > plot(data)
 >
 > Well, is it relationship right? or it
 > is just mathematical fit? If it is
 > right, what theory behind it? I've
 > search for it but until now I not
 > get the theory.
 > Best Regards
 >
 > Muhammad Abduh
 >
 >
 >
 > -= This is automatically added to each message by the mailing script =->
 >
 >