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15 Nov 1971

Volume 55, Issue 10, pp. 4685-5146

Page 1 of 4 Pages Next Page | Jump to Page

Germanium‐Hydrogen‐Lithium Center in α‐Quartz

John A. Weil

J. Chem. Phys. 55, 4685 (1971); http://dx.doi.org/10.1063/1.1675566 (14 pages) | Cited 16 times

Online Publication Date: 9 December 2003

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A new center, denoted by GeHLi2, has been observed by EPR to be present in alpha‐quartz containing germanium, after room temperature x irradiation. The spin Hamiltonian at 8909 MHz and 300°K has been measured, yielding the Zeeman splitting tensor g and the hyperfine coupling tensors Ā (73Ge), Ā (1H), Ā (7Li1), and Ā (7Li2). From the principal values and axis directions, a model for the center of the form Ge3+H−(Li+)2 has been derived. This postulates germanium to be present substitutionally at a silicon site, with the hydride and two lithium ions occurring interstitially nearby. The unpaired electron is thought to be in a Ge orbital a(4s)+b(4p), with ∣a∣2 ∼ 0.18 and ∣b∣2 ∼ 0.35, with considerable spin density also at the hydrogen. The center may be formed from a diamagnetic precursor Ge2+(Li+)2 by reaction with a hydrogen atom.

One‐Center rij Integrals Over Slater‐Type Orbitals

James S. Sims and Stanley A. Hagstrom

J. Chem. Phys. 55, 4699 (1971); http://dx.doi.org/10.1063/1.1675567 (12 pages) | Cited 45 times

Online Publication Date: 9 December 2003

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Expressions are derived for the integrals which arise in calculations of atomic wavefunctions of four or more electrons, utilizing the method of explicit introduction of interelectronic distances rij into a configuration interaction wavefunction (subject to the restriction of at most one rij per configuration). The approach followed in the derivations is similar to one followed by Öhrn and Nordling for three electron integrals; however, in extending the Öhrn and Nordling scheme to four electrons for a basis of s, p, and d Slater‐type orbitals, numerical snags are encountered which have been obviated by an Euler transformation on certain of the auxiliary integrals.

Approximate Numerical Hartree—Fock Method for Molecular Calculations

Karlheinz Schwarz and John W. D. Connolly

J. Chem. Phys. 55, 4710 (1971); http://dx.doi.org/10.1063/1.1675568 (5 pages) | Cited 25 times

Online Publication Date: 9 December 2003

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Calculations are presented which show that the atomic orbitals which result from approximate numerical Hartree—Fock calculations (by the Xα method) are as close to the Hartree—Fock limit for atoms as are those calculated using a double‐zeta basis. Arguments are given which show that the exchange is treated with sufficient accuracy by the Xα method. With the additional ``muffin‐tin'' approximation, which is widely used in solid state calculations, the ``multiple scattering'' formalism can be used for molecules to solve this model Hamiltonian without any further approximation. The exchange is treated with sufficient accuracy, therefore this approach should give the electronic energies as well as the usual type of ab initio calculation, whenever the ``muffin‐tin'' approximation is good, but with 2 or 3 orders of magnitude less computational time.

Diffusivity of 3He, 4He, H2, D2, Ne, CH4, Ar, Kr, and CF4 in (C4F9)3N

R. J. Powell and J. H. Hildebrand

J. Chem. Phys. 55, 4715 (1971); http://dx.doi.org/10.1063/1.1675569 (2 pages) | Cited 4 times

Online Publication Date: 9 December 2003

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An earlier paper from this laboratory reported that diffusion coefficients of gases in CCl4 multiplied by their molecular cross sections are the same for gases heavier than Ne, but that they increase linearly from D2 to 4He with the square of the de Boer quantum parameter A*. The present study of gases in (C4F9)3N includes 3He. For relative cross sections we use, instead of uncertain values of σ2, the ⅔ power of the critical volumes, Vc, accurately known from critical densities. Measured values conform to the equation 102DVc2/3 = 70(1+1.94Λ*2). Diffusion coefficients in CCl4, multiplied by Vc2/3 yield 102DVc2/3 = 70(1+3.00Λ*2). The relative steepness of the two quantum lines is 3.001.94 = 1.60, exactly the same as the ratio of the internal pressures of the two liquids, 3350∕2160.

Trajectory Studies of Atomic Recombination Reactions

A. G. Clarke and G. Burns

J. Chem. Phys. 55, 4717 (1971); http://dx.doi.org/10.1063/1.1675570 (14 pages) | Cited 40 times

Online Publication Date: 9 December 2003

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The radical molecule complex (RMC) theory for bromine atom recombination in the presence of an inert gas M has been tested by computing 3D classical trajectories for BrM+Br collisions. The dissociation energy of BrM was taken to be of the order of one kcal∕mole. Monte Carlo methods were used to select random initial conditions of the BrM molecules with bound and metastable states included. The largest cross sections for the recombination reaction were with deep potential wells and small collision diameters for the Br�M interaction. Heavy third bodies were slightly more effective than light third bodies in promoting the reaction. The velocity averaged cross sections decreased with temperature as T−0.4 for M=Xe, T−0.6 for M=Ar and T−0.9 for M=He. Recombination rate constants, kr, were calculated at 300, 600, 1000, and 1500°K. For argon, with a Br�Ar well depth of 1.0 kcal∕mole, the absolute magnitude and temperature dependence of kr agreed with experiment. For helium and xenon agreement of the calculated and experimental kr values at 300°K was obtained with the same well depth, 1.0 kcal∕mole. The temperature dependence of kr was reasonable for Xe but for He the calculated value of kr at 1000°K was more than a factor of two smaller than the experimental value. The limitations of the RMC model are discussed in the light of these findings. The energy distributions for the bromine molecules formed in the recombination reaction show that the mean total internal energy is close to the dissociation energy but that there are wide spreads of rotational and vibrational energies; recombination does not take place predominantly into a few vibrational levels near the dissociation limit. The trajectory results are compared with the findings of Blake, Browne, and Burns [J. Chem. Phys. 53, 3320 (1970)] who used a Sutherland potential model for the BrM�Br interaction.

Optical and Magnetic Studies of Tripositive Thulium in Octahydrated Sulfate Crystals

E. A. Karlow and J. B. Gruber

J. Chem. Phys. 55, 4730 (1971); http://dx.doi.org/10.1063/1.1675571 (15 pages) | Cited 9 times

Online Publication Date: 9 December 2003

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The optical absorption spectra of single‐crystal Tm2(SO4)3⋅8H2O and Tm3+ in Y2(SO4)3⋅8H2O have been studied in the range from 2500 to 8000 Å at 4.2 and 77°K. Nine [SL]‐J levels were identified including 3P2,1,0, 1I6, 1D2, 1G4, 3F2,3,4. The vibronic, electronic, and temperature‐dependent absorption lines of these multiplets were identified and tabulated. The spectra were studied as a function of magnetic field strength and as a function of orientation in the magnetic field. Zeeman absorption, paraelectric resonance, and zero‐magnetic field optical absorption spectra all indicate a nearly accidental degeneracy in the ground state of tripositive thulium in the octahydrated sulfate salts. The magnetic moment was found to lie in the rectangular plane formed by the crystal's macroscopic habit and inclined at an angle of 46° with respect to the crystal's major habit direction. The crystalline lattice of these salts was found to possess magnetically inequivalent sites. The optical spectra arising from thulium ions in both sites are indistinguishable, but the application of an external magnetic field revealed that the local ionic magnetic moments in these two kinds of sites are inclined at a relative angle of approximately 60°. The observed splitting factor for thulium ions in both sites was found to be 13.4 Lorentz units. The principle features of the magnetic properties of these salts were confirmed by anisotropic paramagnetic susceptibility measurements.

Location of Energy Barriers. IV. Effect of Rotation and Mass on the Dynamics of Reactions A+BC

B. A. Hodgson and J. C. Polanyi

J. Chem. Phys. 55, 4745 (1971); http://dx.doi.org/10.1063/1.1675572 (13 pages) | Cited 64 times

Online Publication Date: 9 December 2003

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In Paper I of the present series a study was made of the effect of barrier location on the dynamics of thermoneutral reaction A+BC→AB+C, for which the atomic masses were mA=mB=mC. Two contrasting potential‐energy hypersurfaces were used; on ``surface I'' the crest of the 7 kcal mole−1 energy barrier was slightly displaced ( ∼ 0.3Å) into the entry valley of the collinear energy surface, whereas on ``surface II'' the crest of the barrier was displaced by the same amount into the exit valley. Precisely the same potential‐energy hypersurfaces have been used in the present work as were used in Paper I. The present work was undertaken to examine the effect (a) of the inclusion of a small but significant amount of rotational energy in the reagents, and (b) of a change in reagent masses from the extreme case L+HH (L ≡ 1 amu,H ≡ 80 amu) to the opposite extreme H+HL. [These mass combinations were identified as extreme cases, the former giving rise to the ``light‐atom anomaly'' and the latter to a maximum of ``mixed energy release,'' in earlier work, see J. Chem. Phys. 44, 1168 (1966)]. The qualitative generalizations introduced in Paper I are found to remain valid despite the introduction of variables (a) and (b), above. Of these generalizations the most important is that reagent translational energy favors reaction on surface I, whereas reagent vibration is the most favorable to reaction on surface II. If barrier location on the ``diagnostic'' collinear potential‐energy surface is to be used as an approximate quantitative guide to reaction dynamics, then the diagnostic surface should be the scaled collinear surface appropriate to the particular mass combination.

Spin—Spin Coupling in Magnetically Condensed Complexes. XII. The Ground State of Tetrakis (N, N′‐dimethylglyoximato) dicopper (II)

Juan F. Villa and William E. Hatfield

J. Chem. Phys. 55, 4758 (1971); http://dx.doi.org/10.1063/1.1675573 (5 pages) | Cited 13 times

Online Publication Date: 9 December 2003

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The ground state of tetrakis (N, N′‐dimethylglyoximato) dicopper (II) is shown to be of triplet multiplicity with the first excited state being a singlet, at 29.8 cm−1 higher in energy. EPR measurements confirm the existence of spin—spin interactions, and a value of D=0.0340 cm−1 was obtained from the half‐field line, Hmin. The other g values obtained from the triplet state spectra were g∥ = 2.155,g⊥ = 2.122 and (g) = 2.134. Cryomagnetic measurements in the low‐temperature range (4.2–55°K) in conjunction with a best fitting procedure yielded the following values for the magnetic parameters: 〈g〉 = 2.157,2J = +29.8 cm−1 and θ = −1.45°K. A superexchange mechanism via the σ orbitals of the �N�O� bridge is proposed to account for the experimental findings. This mechanism includes both intra‐atomic direct exchange and interatomic electron transfer.

Pressure‐Consistent Integral Equations

Frederick Mandel and Richard J. Bearman

J. Chem. Phys. 55, 4762 (1971); http://dx.doi.org/10.1063/1.1675574 (6 pages) | Cited 2 times

Online Publication Date: 9 December 2003

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The behavior of the Hurst and Rowlinson—Carley—Lado pressure‐consistent equations for the Lennard‐Jones (6–12), hard‐sphere, and Gaussian potentials and their dependence on the adjustable parameters m and ϕ are discussed. Numerical solutions of the Hurst and Rowlinson—Carley—Lado equations are compared with the Percus—Yevick, PY2, hypernetted chain, and Monte‐Carlo results. It is shown that the pressure‐consistent equations are more satisfactory for the hard‐sphere potential than the Lennard‐Jones potential.

Moments of NMR Absorption Lines from the Free Induction Decay or Echo of Solids

A. J. Dianoux, S. Sýkora, and H. S. Gutowsky

J. Chem. Phys. 55, 4768 (1971); http://dx.doi.org/10.1063/1.1675575 (4 pages) | Cited 2 times

Online Publication Date: 9 December 2003

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A new method is presented for determining the moments of nuclear magnetic resonance absorption lines from the shape of either the free induction decay or that of the echo. Unlike previously used techniques, this method does not require the assumption of an analytic function for the line shape or the fitting of the experimental decay with a polynomial. A fast, suitably precise and numerically stable algorithm has been developed for performing the integration required by the new method.

Water Cluster Formation Rates of NO+ in He, Ar, N2, and O2 at 296°K

Carleton J. Howard, Howard W. Rundle, and Frederick Kaufman

J. Chem. Phys. 55, 4772 (1971); http://dx.doi.org/10.1063/1.1675576 (5 pages) | Cited 15 times

Online Publication Date: 9 December 2003

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Reaction rates of NO+ and its hydrates, NO+⋅nH2O(n = 1–3), with water were measured in a flow system. The mechanism for conversion of NO+ hydrates to H3O+ hydrates was confirmed, and rate constants for the sequence of six clustering, redissociation, and rearrangement reactions were determined for each of the four carrier gases He, Ar, N2, and O2.

Non‐Steady‐State, Hot Wire, Thermal Conductivity Apparatus

Phil S. Davis, Felix Theeuwes, Richard J. Bearman, and Roger P. Gordon

J. Chem. Phys. 55, 4776 (1971); http://dx.doi.org/10.1063/1.1675577 (8 pages) | Cited 13 times

Online Publication Date: 9 December 2003

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A non‐steady‐state, hot wire apparatus has been constructed to measure the absolute or relative thermal conductivities of fluids. With the use of a four‐lead bare wire probe, a precision of 0.1%, and an absolute accuracy of ±1% have been obtained. A quartz‐coated film sensor is used to obtain relative thermal conductivity data for salt water solutions with a precision of 1% and an over‐all accuracy of ±2%. A comparison is made with experimental data available from the literature. For toluene, a comparison is made with the extrapolated values of Poltz and Jugel from which errors due to radiation have been eliminated for the parallel plate apparatus. The values agree within experimental error.

Low‐Frequency Vibrational Light Scattering in Viscous Liquids

Reuben Shuker and Robert W. Gammon

J. Chem. Phys. 55, 4784 (1971); http://dx.doi.org/10.1063/1.1675578 (5 pages) | Cited 34 times

Online Publication Date: 9 December 2003

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The theory of Raman scattering from the vibrations of amorphous materials is applied to the spectra of B2O3 glass and its melt. Experimental evidence is obtained indicating that low frequency scattering in the melt liquid is also due to first order scattering from intermolecular vibrational states. The relationship among several scattering mechanisms in liquids is discussed.

Vibrational Frequencies and Force Constants for Tetrahedral MgX4−2 (X=Cl, Br, and I) in MgX2�KX Melts

Victor A. Maroni

J. Chem. Phys. 55, 4789 (1971); http://dx.doi.org/10.1063/1.1675579 (4 pages) | Cited 27 times

Online Publication Date: 9 December 2003

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Raman spectra are reported for the species present in MgX2�KX melts (X=Cl, Br, and I) with X−1∕Mg+2 mole ratios near 4.0. The observation of one polarized band and three depolarized bands for each halide melt is consistent with the existence of the tetrahedral complexes MgCl4−2, MgBr4−2, and MgI4−2. All the observed frequencies are calculated within 1 cm−1 using a Urey—Bradley force field which consists of an Mg�X stretching constant, an X�Mg�X bending constant, and an X⋅⋅⋅X repulsion constant.

Variational Methods in the Wave Operator Formalism. A Unified Treatment for Bound and Quasibound Electronic and Molecular States

David A. Micha and Erkki Brändas

J. Chem. Phys. 55, 4792 (1971); http://dx.doi.org/10.1063/1.1675580 (6 pages) | Cited 31 times

Online Publication Date: 9 December 2003

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The wave operator formalism of Löwdin, heretofore used to describe states belonging to the discrete energy spectrum, has been extended to unify the treatment of bound and quasibound (or decaying) states. The approach makes use of an arbitrary reference function that may be chosen to approximate the physical state at short distances. Real and complex eigenvalues are obtained, respectively, for bound and quasibound states from an implicit equation, valid for all coupling strengths. Resonance positions and linewidths are explicitly independent of energy. Variational principles of the Lippmann—Schwinger type are presented which apply to states with either bound‐state or decay boundary conditions. Particular cases leading to minimization or maximization principles for real energies are discussed. The formalism is considered in connection with decaying electronic states of atoms and decaying molecular states.

Electronic Splitting between the 2B1 and 2A1 States of the NH2 Radical

Charles F. Bender and Henry F. Schaefer

J. Chem. Phys. 55, 4798 (1971); http://dx.doi.org/10.1063/1.1675581 (6 pages) | Cited 70 times

Online Publication Date: 9 December 2003

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Theoretical calculations are reported for the ground and first excited states of NH2. A contracted Gaussian basis of four s, two p, and one d functions is centered on the nitrogen atom, while for hydrogen two s and one p functions are used. Both self‐consistent‐field (SCF) and multiconfiguration first‐order wave‐functions have been computed, the latter using the iterative natural‐orbital method. Two new theoretical ideas were tested and found useful: (a) Bunge's partitioning of degenerate spaces and (b) a procedure for generating uniform sets of starting orbitals for multiconfiguration calculations. For the 2B1 state the SCF, CI, and experimental geometries are θ=105.4°, r=1.019 Å; θ=102.7°, r=1.055 Å; θ = 103.3±0.5, r = 1.024±0.005Å. The analogous results for the 2A1 state are θ=141.9°, r=0.997 Å; θ144.7°, r=1.010 Å; θ = 144±5, r = 0.97–1.00Å. For the upper 2A1 state the barrier to linearity is 1370 cm−1 in the SCF approximation, 1030 cm−1 from the correlated wavefunctions, and 770±100 cm−1 experimentally. The 2B1—2A1 splitting Te is predicted to be 12 800 cm−1 (SCF) and 14 500 cm−1 (CI), whereas the experimental value is thought to be ∼ 11 000 cm−1. Potential curves are shown and electronic structure considerations discussed.

Irradiation Damage and Semiconducting Properties of CdF2:Eu

A. Tzalmona and P. S. Pershan

J. Chem. Phys. 55, 4804 (1971); http://dx.doi.org/10.1063/1.1675582 (8 pages) | Cited 13 times

Online Publication Date: 9 December 2003

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Thermoluminescence data have been used to unravel the fluorescence spectrum of Eu3+ in the insulating CdF2⋅host. Optical absorption and EPR measurements of semiconducting CdF2:Eu are the bases of a model of this semiconductor.

Kinetic Salt Effects on the Aquation Reaction of the Azidopentaaquochromium (III) Ion and Predictions of the Mayer Theory

A. Indelli and R. De Santis

J. Chem. Phys. 55, 4811 (1971); http://dx.doi.org/10.1063/1.1675583 (6 pages) | Cited 1 time

Online Publication Date: 9 December 2003

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The rate of the reaction of aquation of the azidopentaaquochromium (III) ion has been measured at two different concentrations of hydrogen ion in the presence of a number of salts. The values of k1 and k0 of the equation
math
were calculated and both show positive salt effects and obey the Olson‐Simonson rule. Calculations performed using the Mayer theory in the approximation `` DHLL+B2'' have shown that at high dilution both these effects can be rationalized using appropriate values of the distances of closest approach. The possibility of using this form of the Mayer theory for extrapolation purposes is suggested. The use of different distances of closest approach for different pairs of ions does not lead to any inconsistency.

On a Generalized Einstein Theory for the Thermodynamics of Planar Surfaces and Microcrystallites

Farid F. Abraham and J. V. Dave

J. Chem. Phys. 55, 4817 (1971); http://dx.doi.org/10.1063/1.1675584 (5 pages) | Cited 14 times

Online Publication Date: 9 December 2003

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We present a generalized Einstein theory to predict the thermodynamic properties of planar surfaces and microcrystallites which Nishioka et al. have obtained from numerical normal mode calculations. An important aspect of our model is that it identifies the important physical features governing the structure of the vibrational free energy as a function of microcrystallite size.

Energy‐Transfer Processes in Monochromatically Excited Iodine Molecules. V. Rotational Energy Transfer in Argon‐Excited I2

R. B. Kurzel, J. I. Steinfeld, D. A. Hatzenbuhler, and G. E. Leroi

J. Chem. Phys. 55, 4822 (1971); http://dx.doi.org/10.1063/1.1675585 (11 pages) | Cited 64 times

Online Publication Date: 9 December 2003

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Rotationally resolved energy‐transfer rates have been measured for I2 excited to J′ = 11 and 15 of v′ = 43 of the B 3Π0u+ state by the argon laser line at 5145 Å, for accompanying changes in v′ of 0, ±1, ±2, and ±3, in collisions with ground‐state I2, H2, He, and Ne. In all of these collisions, there is a persistence of rotational state, ∣ ΔJ′ ∣ ≤ 14 being favored; however, broader distributions are found, as expected, for collisions with larger ∣Δ v∣'s or with heavier collision partners. The microscopic rate constants are asymmetric to ΔJ′>0, as expected for (T/B)1/2 ≈ 80.

Phosphorescence of Benzophenone, Benzophenone‐d10, and Decafluorobenzophenone in Rigid Glasses and Crystals under Pressure

Jerry Simpson and Henry Offen

J. Chem. Phys. 55, 4832 (1971); http://dx.doi.org/10.1063/1.1675586 (5 pages) | Cited 4 times

Online Publication Date: 9 December 2003

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The phosphorescence of benzophenone, benzophenone‐d10, and decafluorobenzophenone has been studied as a function of pressure (0–30 kbar) at 77°K in nonpolar and polar glasses, as well as from molecules at pressure‐induced defect sites in the corresponding crystals. The pressure shift in the triplet spectra is in the order ΔνF>ΔνD≳ΔνH, while lifetimes are shortened 15%−25% at 30 kbar. The blue shift in hydroxylic glasses and the red shift observed both in hydrocarbon glasses and at crystal defects are rationalized in terms of hydrogen bonding, dielectric interactions, and repulsive interactions, respectively.

Symmetry Adapted Perturbation Theories: Application to a Generalized Eigenvalue Equation for the Hydrogen Molecular Ion

C. Laughlin and A. T. Amos

J. Chem. Phys. 55, 4837 (1971); http://dx.doi.org/10.1063/1.1675587 (6 pages) | Cited 5 times

Online Publication Date: 9 December 2003

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Analogues of the Murrell—Shaw, Musher—Amos, and van der Avoid—Hirschfelder symmetry adapted perturbation theories are devised for the case of a generalized eigenvalue equation. The new procedures are applied to the hydrogen molecule ion and perturbation energies through second order are calculated at various internuclear distances.

Pulsed Nitrogen—Proton Double Resonance Study of the Ferroelectric Transition in Triglycine Sulfate

R. Blinc, M. Mali, R. Osredkar, A. Prelesnik, I. Zupančič, and L. Ehrenberg

J. Chem. Phys. 55, 4843 (1971); http://dx.doi.org/10.1063/1.1675588 (6 pages) | Cited 29 times

Online Publication Date: 9 December 2003

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The technique of nuclear magnetic pulsed double resonance in the rotating frame has been used to study the changes in the 14N quadrupole interactions in a triglycine sulfate (TGS) single crystal on going from the paraelectric to the ferroelectric phase. The 14N electric field gradient tensors have been determined above as well as below Tc. The most significant effect of the ferroelectric transition is a large change in the time averaged value of the C�N bond direction of glycine I and the onset of chemical nonequivalence of glycines II and III due to an ordering of the protons in the short O�H⋅⋅⋅O bond. The results show that the phase transition in TGS is of the order—disorder type as far as the glycine groups are concerned.

9Be Quadrupole Perturbed NMR Study of the Ferroelectric Transition in Deuterated Triglycine Fluoberyllate

R. Blinc, J. Slak, and J. Stepišnik

J. Chem. Phys. 55, 4848 (1971); http://dx.doi.org/10.1063/1.1675589 (3 pages) | Cited 7 times

Online Publication Date: 9 December 2003

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The quadrupole perturbed magnetic resonance spectra of 9Be in a deuterated triglycine fluoberyllate single crystal have been studied as a function of temperature and crystal orientation, and the electric field gradient (EFG) tensors at the Be sites have been determined in the para‐ and in the ferroelectric phase. The data show that the main effect of the ferroelectric transition is a shift of the Be ion away from the twofold b axis where it lies in the paraelectric phase and a rotation of the two minor principal axes of the 9Be EFG tensor for θ = ±25° away from the average, paraelectric direction. The results can be understood in terms of the dynamic order—disorder model, proposed by Hoshino, Okaya, and Pepinsky.

Zero‐Point Vibrational Corrections to One‐Electron Properties of the Water Molecule in the Near‐Hartree—Fock Limit

W. C. Ermler and C. W. Kern

J. Chem. Phys. 55, 4851 (1971); http://dx.doi.org/10.1063/1.1675590 (10 pages) | Cited 73 times

Online Publication Date: 9 December 2003

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The zero‐point vibrational motion of the water molecule in its ground electronic state is analyzed with a near‐Hartree—Fock potential energy surface constructed from a (9s5p2d∕4s1p) ∕[4s3p2d∕2s1p] basis set of contracted Gaussian orbitals. The harmonic and cubic force constants relative to the computed minimum are obtained, and a normal coordinate analysis is carried out for several isotopic variants. A set of one‐electron properties including molecular moments, field gradients, forces, and densities is computed at each point on the potential surface, and then averaged over the zero‐point motion with a vibrational wavefunction which contains anharmonicity terms through the cubic constants. The vibrational corrections are typically about 1% of the equilibrium values, but are as large as 20% in cases such as the 17O quadrupole coupling constant along the C2 axis. The theoretical isotope shifts for the quadrupole moments of H2O and D2O are in good agreement with experiment. Predictions are made for isotope shifts in other properties. A b initio values of the bond and angle displacement coordinates and their root‐meansquare amplitudes are also determined.
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