Electric Polarizability and Hyperpolarizability of Carbon Monoxide

Maroulis, George

doi:10.1021/jp960412n

Cited by 125 publications

(88 citation statements)

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“…In this work, we calculated the polarizabilities by using the coupled perturbed Hartree-Fock (CPHF) approach at the B3LYP/aug-cc-pVTZ level. A test B3LYP/aug-cc-pVTZ calculation performed on a CO molecule gave a polarizability of 1.95 Å 3 , which is in good agreement with the experimental [41] and theoretical [42] value of 1.95 Å 3 . The calculated polarizabilities are also shown in figure 1.…”

Section: Computational Detailssupporting

confidence: 78%

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters

Lan

Kang

Niu

2012

Int J of Quantum Chemistry

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We performed a comprehensive study of the size-, shape-, and composition-dependent polarizabilities of Si m C n (m, n = 1-4) clusters on the basis of the density-functional-based coupled perturbed Hartree-Fock calculations. We found better correlations between the polarizabilities and both the binding energies (E b ) and change in charge distribution (∆q) than the energy gaps (E g ). The α values exhibit overall decreasing and increasing trends with increases in the E b and ∆q values, respectively. For isomers with the same E b values and different polarizabilities, ∆q can well explain the difference in polarizabilities. The π-electron delocalization effect is the best factor for understanding the shape-dependence. For a given m/n value, the linear clusters have an obviously larger polarizability than both the prolate and compact clusters, irrespective of the cluster size. We fit a quantitative expression [α = A -(A -B) × exp(-k(m/n))] to describe the composition-dependent polarizabilities.Keywords: Binding energy, energy gap, charge distribution, polarizability, silicon carbide cluster IntroductionIn the last 20 years, the (hyper)polarizabilities of small semiconductor clusters such as gallium arsenide (GaAs), silicon (Si), silicon carbide (SiC), and aluminum phosphide (AlP) clusters have attracted much attention . Experimental studies have shown that the static polarizabilities of Si m (m = 9-50) and Ga m As n (m + n = 5-30) clusters fluctuate around their corresponding bulk values [12]. These experimental results have motivated many theoretical studies of the polarizabilities of Si and GaAs clusters [1, 2, 4, 6 -9, 16, 26, 27]. Theoretical studies have shown that the size of the polarizability directly or indirectly depends on various factors such as the cluster size, cluster shape, cluster composition, energy gap, binding energy, ionization potential, and so on. The size-dependence of the polarizabilities has been well known for Si and GaAs clusters. For small Si m (m < 10) and Ga n As m (n + m < 8) clusters, the theoretical polarizabilities are higher than the bulk value and decrease with an increase in cluster size [1,2,9,12,16], as indicated by the number of atoms in a cluster. For mediate-size Si m (m = 9-50) and

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Section: Computational Detailssupporting

confidence: 78%

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters

Lan

Kang

Niu

2012

Int J of Quantum Chemistry

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“…The LB94 values are too low, on the other hand, but for ␥ they seem to be slightly preferable to the HF, LDA, and BLYP values. Using the large basis set CCSD͑T͒ results by Maroulis 47 as the benchmark, the HF value for ␤ ʈ ͓Maroulis obtained 24.75, 47 ␥ xxxx ϭ1100 ͑1200͒; ␥ zzzz 610 ͑630͒, which is quite satisfactory. Once again, the numerical and basis set errors in our results seem to be substantially smaller than the errors introduced through the approximations for the xc potential.…”

Section: F Comentioning

confidence: 90%

Accurate density functional calculations on frequency-dependent hyperpolarizabilities of small molecules

Gisbergen

Snijders

Baerends

1998

The Journal of Chemical Physics

173

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In this paper we present time-dependent density functional calculations on frequency-dependent first (␤) and second (␥) hyperpolarizabilities for the set of small molecules, N 2 , CO 2 , CS 2 , C 2 H 4 , NH 3 , CO, HF, H 2 O, and CH 4 , and compare them to Hartree-Fock and correlated ab initio calculations, as well as to experimental results. Both the static hyperpolarizabilities and the frequency dispersion are studied. Three approximations to the exchange-correlation ͑xc͒ potential are used: the widely used Local Density Approximation ͑LDA͒, the Becke-Lee-Yang-Parr ͑BLYP͒ Generalized Gradient Approximation ͑GGA͒, as well as the asymptotically correct Van Leeuwen-Baerends ͑LB94͒ potential. For the functional derivatives of the xc potential the Adiabatic Local Density Approximation ͑ALDA͒ is used. We have attempted to estimate the intrinsic quality of these methods by using large basis sets, augmented with several diffuse functions, yielding good agreement with recent numerical static LDA results. Contrary to claims which have appeared in the literature on the basis of smaller studies involving basis sets of lesser quality, we find that the static LDA results for ␤ and ␥ are severely overestimated, and do not improve upon the ͑underestimated͒ Hartree-Fock results. No improvement is provided by the BLYP potential which suffers from the same incorrect asymptotic behavior as the LDA potential. The results are however clearly improved upon by the LB94 potential, which leads to underestimated results, slightly improving the Hartree-Fock results. The LDA and BLYP potentials overestimate the frequency dependence as well, which is once again improved by the LB94 potential. Future improvements are expected to come from improved models for asymptotically correct exchange-correlation potentials. Apart from the LB94 potential used in this work, several other asymptotically correct potentials have recently been suggested in the literature and can also be expected to improve considerably upon the relatively poor LDA and GGA results, for both the static properties and their frequency dependence.

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“…Recently, we developed a refined model that uses fluctuating charges on the C and O atom sites and at the center of mass (9). This model reproduces high-level ab initio calculations of the dipole and quadrupole moment over a wide range of intermolecular separations (10,11) and allows the calculation of the infrared spectrum associated with the CO vibration. The model correctly describes the experimentally observed existence of the docking site within the distal heme pocket as well as the migration of the ligand through the protein to the xenon-4 pocket, which has been observed for various mutants (12,13).…”

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confidence: 99%

CO migration in native and mutant myoglobin: Atomistic simulations for the understanding of protein function

Nutt

Meuwly

2004

Proc. Natl. Acad. Sci. U.S.A.

101

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Molecular dynamics simulations of the events after the photodissociation of CO in the myoglobin mutant L29F in which leucine is replaced by phenylalanine are reported. Using both classical and mixed quantum-classical molecular dynamics calculations, we observed the rapid motion of CO away from the distal heme pocket to other regions of the protein, in agreement with recent experimental results. The experimentally observed and calculated infrared spectra of CO after dissociation are also in good agreement. We compared the results with data from simulations of WT myoglobin. As the time resolution of experimental techniques is increased, theoretical methods and models can be validated at the atomic scale by direct comparison with experiment. R ecently, the time-resolved infrared spectrum and x-ray diffraction of photodissociated 13 CO in myoglobin (Mb) have been reported for a particular mutant, L29F (1). In this mutant the leucine (L) residue at position 29 is replaced by a phenylalanine (F) (see Fig. 1). This mutation introduces a bulky phenyl side chain into the distal heme pocket that can be expected to have an impact on the dynamics after photodissociation. It was previously found that the equilibrium constants for O 2 binding are larger by a factor of 15 in L29F compared to native Mb (2). This difference was interpreted as due to stabilizing interactions between the bound dioxygen and atoms of the phenyl ring. The infrared experiments, carried out at 283 K, found that the characteristic infrared absorption band for CO in the native Mb changes profoundly in the case of the L29F mutant (1). The well known bimodal distribution, indicative of the population of different binding sites [conformational substates B1 and B2, which differ in the orientation of the CO (3, 4), and possibly B3, which can only be populated by extended illumination in native MbCO (5)] is fundamentally altered. For L29F, the bimodal structure of the infrared spectrum disappears after Ϸ100 ps, whereas for native Mb it persists for 100 ns. This effect was explained by the escape of CO from the primary docking site within the distal heme pocket (Fig. 1) to neighboring sites within the protein on a time scale three orders of magnitude faster than in the case of native Mb (1).Previous theoretical investigations of the ligand dynamics of CO in myoglobin focused mostly on the short time scale and have considered effects after dissociation of the ligand from the iron on the picosecond time scale (6, 7). Some of the investigations used a three-site model for the CO ligand (8). This model correctly describes the static dipole and quadrupole moment of CO. Recently, we developed a refined model that uses fluctuating charges on the C and O atom sites and at the center of mass (9). This model reproduces high-level ab initio calculations of the dipole and quadrupole moment over a wide range of intermolecular separations (10, 11) and allows the calculation of the infrared spectrum associated with the CO vibration. The model correctly describes the experimen...

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Electric Polarizability and Hyperpolarizability of Carbon Monoxide

Cited by 125 publications

References 56 publications

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters

Accurate density functional calculations on frequency-dependent hyperpolarizabilities of small molecules

CO migration in native and mutant myoglobin: Atomistic simulations for the understanding of protein function

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Electric Polarizability and Hyperpolarizability of Carbon Monoxide

Cited by 125 publications

References 56 publications

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of SimCn (m, n = 1–4) clusters

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of SimCn (m, n = 1–4) clusters

Accurate density functional calculations on frequency-dependent hyperpolarizabilities of small molecules

CO migration in native and mutant myoglobin: Atomistic simulations for the understanding of protein function

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Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters

Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of Si_mC_n (m, n = 1–4) clusters