Ab initio MO SCF

Rode" has reported the results of ab initio MO-SCF calculations on IF (n = 1, 3, or 5) and has used the results to discuss electronic structures and physical... 

Thus, both states are correlated with 1o log IjcJ, of the hypothetical linear molecule [12]. The complete electronic configuration for the X ground state [14, 15] is based on an ab initio MO-SCF calculation of orbital energies [14] ... 

The 2b2 orbital is shown by ab initio MO-SCF calculations to be composed of P3py and His and to be P-H bonding with a small H-H antibonding contribution [10]. For its bonding character, see also [1]. 

Net atomic charges at P and H and the dipole moment p from an ab initio MO-SCF calculation (unrestricted Hartree-Fock method) are shown below [15] ... 

Electron propagator theory (EPT) yielded a vertical value of 1.160 eV [28] (see also [29 to 31 ]), MP2 theory gave 1.162 eV (zero point correction included) [32], MP4 theory (using isogyric comparisons with the H2 molecule) 1.23 eV [33], and MP4 + quadratic Cl calculations 1.20 eV [14]. Compare also a 1985-review on theoretical calculations of A [34]. HF calculations on PH2 yielded Koopmans Theorem (KT) electron detachment energies, which depend strongly on the basis sets used [35]. Older ab initio MO-SCF calculations gave unsatisfactory results [17]. 

The stretching and bending force constants ki and k2 have been estimated using data of the related PH3 molecule or theoretically calculated. ki =3.10 mdyn/A for ground-state PH2 was taken from PH3 [7]. k =7.260 mdyn/A and k2 = 0.01021 mdyn/A were calculated by an ab initio MO-SCF method [37]. Apparently more reliable data for k2 are given below for the ground state X 2Bi and the excited state A Ai (for units, see also the remarks) ... 

Net atomic charges of about -0.2 at each H were calculated with an ab initio MO-SCF method [2], with the semiempirical CNDO/2 method [11], and with another semiempirical method using localized bond orbitals for Cl [12]. A lower value came from an EH calculation [3]. A radial electron density distribution was calculated within the united-atom approximation [10]. Two different dipole moments were obtained with an MO-SCF calculation (yielding also quadrupole and octupole moments) [2] and with the electron propagator theory (EPT) [13]. 

The diamagnetic shielding at P and H was calculated by an ab initio MO-SCF method for the calculated equilibrium geometry [17]. 

From ab initio MO-SCF calculations, AH is obtained as a difference of total energies, Ej(cis-N2F2) - Ej(trans-N2F2). In order to get a meaningful result, calculations have to be carried out at fully-optimized molecular geometries [9]. However, so far the magnitude and size of AH,... 

Ab initio MO SCF calculations showed that the ground state HeN( Il) is unbound [1]. CNDO/2 calculations of the binding energy and equilibrium distance were reported in [2]. 

HeN in its ground state represents a van der Waals complex, whereas in the excited state HeN is covalently bound [4]. An earlier computation at an ab initio SCF level likewise yielded a weak bond in HeN (X Z ) of about 7 kJ/mol [5]. Other ab initio MO SCF calculations yielded a weakly bound ground state, one highly and two very weakly bound excited states [6]. CNDO/2 calculations of the binding energy and equilibrium distance were reported in [7]. 

XeN ions were observed mass spectrometrically in mixtures of xenon with nitrogen [16, 35] as a product of the reaction (N2 ) + Xe XeN -h N [16]. The ionization energy Ej = 21.1 2.2 eV for XeN was obtained by charge-stripping mass spectrometry, where the monocation XeN was used as precursor for XeN [11]. On the basis of ab initio MO SCF calculations on HeN and NeN, it was assumed that XeN salts could be prepared [6]. 

The types of (Gaussian) basis sets used in ab initio MO SCF theory have been described elsewhere. It may be helpful to list a few references as examples.The basis set designation in quantiam chemistry appears to be mysterious for non-specialists. However, it frequently has been explained,e.g. recently in a succinct form on current levels of theory. In order to characterize the theoretical level which has been employed for the PES calculation, a double-slash notation is used, introduced by Pople. It characterizes the method and basis set which are used for calculating stationary points of PES ("geometry optimization ) by the information found after the double slashes. The more sophisticated level for subsequent single point calculations of the PES is designated by the information preceding the double slashes. 

Ab initio MO-SCF calculations have been done for thiiran, thiiran 1-oxide, and thiiran 1,1-dioxide. " Variations in carbon-carbon bond distances are... 

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