Dissociation Curve

UHF and RHF dissociation curves for H2. (Figure adapted from Szabo A,NS Ostlund 1982. Modem antum Chemistry. Introduction to Advanced Electronic Structure Theory. New York, McGraw-Hill.)... 

If we were to calculate the potential energy V of the diatomic molecule AB as a function of the distance tab between the centers of the atoms, the result would be a curve having a shape like that seen in Fig. 5-1. This is a bond dissociation curve, the path from the minimum (the equilibrium intemuclear distance in the diatomic molecule) to increasing values of tab describing the dissociation of the molecule. It is conventional to take as the zero of energy the infinitely separated species. 

Figure 6-19. Bond dissociation curve showing the different zero-point vibrational energies of isotopic species R-H and R-D.

Figure 6-20. Bond dissociation curve showing that the average R-H bond distance is greater than the R-D bond distance because of their zero-point energy difference.

Figure 11.1 shows the bond dissociation curve at the HF level with the STO-3G, 3-21G, 6-31G(d,p), cc-pVDZ and cc-pVQZ basis sets. The total energy drops considerably upon going from the STO-3G to the 3-21G and again to the 6-3IG(d,p) basis. This is primarily due to the improved description of the oxygen Is-orbital. The two different... 

Figure 11.1 Bond dissociation curves for H2O at the HF level, absolute energies...

Figure 11.4 RHF, UHF and PUHF dissociation curves for H2O near the instability point...

Figure 11.5 RMP2, UMP2 and PUMP2 dissociation curves for H2O...

Figure 11,13 Bond dissociation curve for unrestricted DPT methods...

Fig. 27. Dissociation curves for /) oxyhaemoglobin in solution 2) oxyhaemoglobin in human red cells and 3) immobilized haemoglobin. 37 °C, pH 7.4 pC02 40 Torr, p02 0-150 Torr...

THE OXYGEN DISSOCIATION CURVES FOR MYOGLOBIN HEMOGLOBIN SUIT THEIR PHYSIOLOGIC ROLES... 

Table 1. shows the total energies obtained using the RHF method for 1. LCAO minimal basis set STO-IG for the sake of comparison with FSGO, 2. FSGO in its symmetric and broken symmetry solutions and, 3. LCAO minimal basis set STO-3G in order to allow a safer comparison with the quality of the subminimal basis used in the FSGO technique. The dissociation curves are given in Figure 1. 

Figure 1 Dissociation curve for the hydrogen molecule (energy and distances in a.u.)...

Describe the physiological significance of the steep and plateau portions of the oxyhemoglobin dissociation curve... 

The P02 of blood is the major factor determining the amount of oxygen chemically combined with hemoglobin, or the percent of hemoglobin saturation. The relationship between these two variables is illustrated graphically by the oxyhemoglobin dissociation curve (see Figure 17.6). This relationship is not... 

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