Calculation of internal valence force constants for XY4 (Td) tetrahedral molecules

Gómez, M. Fernández; González, Juan Jesús López; Rajamanickam, N.; Torres, Emilio Martínez

doi:10.1016/0022-2860(92)80130-a

Cited by 11 publications

(2 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The properties of neutral germanium fluorides GeF n ( n = 1−5) have been intensively investigated over the years by various experimental and theoretical methods, − not only for fundamental reasons but also for their active role in the fine processing of semiconductors. − More recently, the structure, stability, and thermochemistry of the corresponding anionic species GeF n - ( n = 1−5) have been systematically investigated by density functional methods, and discussed in connection with previous related experimental and theoretical data. 3j,k,− ,− As for cationic germanium fluorides, experimental and theoretical studies 55a,61 indicate that, in the ground state, GeF 4 + is unstable and prone to dissociate into GeF 3 + and atomic fluorine. On the other hand, all the other ground-state GeF n + ( n =1−3) are quite stable in the gas phase and abundantly detected, for example, from the electron impact fragmentation of GeF 4 55a.…”

Section: Introductionmentioning

confidence: 99%

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

et al. 2006

View full text Add to dashboard Cite

The structure, harmonic frequencies, enthalpies of formation, and dissociation energies of the GeF(n)(+) cations (n = 1-3) and of their neutral counterparts GeF(n) have been investigated at the MP2 and CCSD(T) levels of theory and discussed in connection with previous experimental and theoretical data. The CCSD(T,full)/cc-pVTZ-optimized geometries and MP2(full)/6-311G(d) harmonic frequencies are 1.744 A and 668.0 cm(-1) for GeF((2)Pi), 1.670 A and 798.6 cm(-1) for GeF(+)((1)Sigma(+)), 1.731 A/97.4 degrees and 267.0 (a(1))/673.1 (b(2))/690.6 (a(1)) cm(-1) for GeF(2)(C(2)(v),(1)A(1)), 1.666 A/116.9 degrees and 202.3 (a(1))/769.6 (a(1))/834.6 (b(2)) cm(-1) for GeF(2)(+)(C(2)(v),(2)A(1)), 1.706 A/112.2 degrees and 214.4 (e)/273.1 (a(1))/699.6 (a(1))/734.1 (e) cm(-1) for GeF(3)(C(3)(v),(2)A(1)), and 1.644 A and 211.4 (e')/229.9 (a(2)' ')/757.4 (a(1)')/879.3 (e') cm(-1) for GeF(3)(+)(D(3)(h),(1)A(1)). These calculated values are in excellent agreement with the experimental data reported for GeF, GeF(+), and GeF(2), and should be therefore of good predictive value for the still unexplored GeF(2)(+), GeF(3), and GeF(3)(+). The comparison of the CCSD(T,full)/cc-pVTZ enthalpies of formation at 298.15 K, -11.6 (GeF), -125.9 (GeF(2)), -180.4 (GeF(3)), 158.4 (GeF(+)), 134.1 (GeF(2)(+)), and 44.8 (GeF(3)(+)) kcal mol(-1), with the available experimental data, especially for the cations, shows discrepancies which suggest the need for novel and more refined measurements. On the other hand, the computed adiabatic ionization potentials of GeF, 7.3 eV, GeF(2), 11.2 eV, and GeF(3), 9.7 eV, are in good agreement with the available experimental estimates.

show abstract

Section: Introductionmentioning

confidence: 99%

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

et al. 2006

View full text Add to dashboard Cite

show abstract

“…However, the issue of the completeness and nonredundancy of a set of internal coordinates may still arise. − The internal coordinates must be chosen in a manner that all vibrational modes can be properly described (i.e., the chosen internal coordinates form a complete set), but at the same time they must uniquely define the potential energy V . ,, A counterexample is the inclusion of all three bond lengths and all three bond angles of a triangular molecule, see for instance ref concerning the cyclic C 3 H 6 molecule. There have been several different sets of internal coordinates previously proposed for various categories of molecules (see for example refs − ). Among them, for example, the Pulay coordinates have been shown to accelerate the geometry optimization process; however, they can suffer from redundancy issues .…”

Section: Introductionmentioning

confidence: 99%

Efficient Procedure for the Numerical Calculation of Harmonic Vibrational Frequencies Based on Internal Coordinates

Miliordos

Xantheas

2013

J. Phys. Chem. A

View full text Add to dashboard Cite

We propose a general procedure for the numerical calculation of the harmonic vibrational frequencies that is based on internal coordinates and Wilson's GF methodology via double differentiation of the energy. The internal coordinates are defined as the geometrical parameters of a Z-matrix structure, thus avoiding issues related to their redundancy. Linear arrangements of atoms are described using a dummy atom of infinite mass. The procedure has been automated in FORTRAN90 and its main advantage lies in the nontrivial reduction of the number of single-point energy calculations needed for the construction of the Hessian matrix when compared to the corresponding number using double differentiation in Cartesian coordinates. For molecules of C1 symmetry the computational savings in the energy calculations amount to 36N - 30, where N is the number of atoms, with additional savings when symmetry is present. Typical applications for small and medium size molecules in their minimum and transition state geometries as well as hydrogen bonded clusters (water dimer and trimer) are presented. In all cases the frequencies based on internal coordinates differ on average by <1 cm(-1) from those obtained from Cartesian coordinates.

show abstract

High‐resolution stimulated Raman spectroscopy and analysis of the ν₁, 2ν₁–ν₁, ν₂, 2ν₂, and 3ν₂–ν₂ bands of CF₄

Boudon

Bermejo

Martínez

2013

J Raman Spectroscopy

View full text Add to dashboard Cite

The spectra of the ν1, 2ν1–ν1, ν2, 2ν2, and 3ν2–ν2 bands of CF4 were obtained with a quasi‐continuous wave stimulated Raman spectrometer. These five bands were studied at a temperature of 135 and 300 K (for the hot bands). The spectrum of ν1 was obtained at a sample pressure of 2 mbar. For the spectra of the other regions, which are much weaker, higher pressures were used. The analysis has been performed thanks to the xtds and spview softwares developed in Dijon for such highly symmetric molecules. Combining the present results with a previous infrared study, we could determine a very accurate value for the C–F equilibrium bond length, i.e. re = 1.31588(6) Å. Copyright © 2013 John Wiley & Sons, Ltd.

show abstract

Calculation of internal valence force constants for XY4 (Td) tetrahedral molecules

Cited by 11 publications

References 18 publications

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

Efficient Procedure for the Numerical Calculation of Harmonic Vibrational Frequencies Based on Internal Coordinates

High‐resolution stimulated Raman spectroscopy and analysis of the ν₁, 2ν₁–ν₁, ν₂, 2ν₂, and 3ν₂–ν₂ bands of CF₄

Contact Info

Product

Resources

About

Calculation of internal valence force constants for XY4 (Td) tetrahedral molecules

Cited by 11 publications

References 18 publications

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeFn/GeFn+ (n = 1−3)

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeFn/GeFn+ (n = 1−3)

Efficient Procedure for the Numerical Calculation of Harmonic Vibrational Frequencies Based on Internal Coordinates

High‐resolution stimulated Raman spectroscopy and analysis of the ν1, 2ν1–ν1, ν2, 2ν2, and 3ν2–ν2 bands of CF4

Contact Info

Product

Resources

About

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeF_n/GeF_n⁺ (n = 1−3)

High‐resolution stimulated Raman spectroscopy and analysis of the ν₁, 2ν₁–ν₁, ν₂, 2ν₂, and 3ν₂–ν₂ bands of CF₄