Calculation Of Electric Dipole Moments Research Articles

Difluorinated cyclopentadithiophene derivatives for green emitters in organic light-emitting diodes: A theoretical investigation

Two types of difluorinated conjugated systems incorporating bridged cyclopentadithiophene, alternating fumaronitrile and 1,3,4-oxadiazole were designed and theoretically studied by density functional theory and its time-dependent extension with the B3LYP hybrid functional and the 6–311g(d,p) and 6–311++g(d,p) basis sets in tetrahydrofuran. The designed materials are denoted FCFO-1 (>CO) and FCFO-2 (>CC–(CN)2. The electronic band gap ranges from 2.46 eV (FCFO-1) to 2.30 eV (FCFO-2). The difference in optical behaviors may originate from the effect of the bridging group on cyclopentadithiophene derivatives. The materials were examined as green emitters (519–564 nm). Organic light-emitting diodes based on these new fluorescent materials [indium tin oxide anode (100 nm)/N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (hole-injection layer) (150 nm)/FCFO-1 or FCFO-2 (50 nm)/Al cathode (100 nm)], were theoretically designed. The current-voltage characteristics were simulated, and the threshold voltages were estimated to be 3.25 V for FCFO-1 and 2.17 V for FCFO-2. Electric dipole moment calculations show the molecules possess large electric dipole moments (approximately 9.88 D for FCFO-1 and approximately 11 D for FCFO-2) and they thus exhibit excellent nonlinear optical properties.

Reappraisal of P, T-odd parameters from the improved calculation of electric dipole moment of 225Ra atom

By employing the recently developed relativistic normal coupled-cluster theory, we obtained the electric dipole moment (EDM) of 225Ra due to nuclear Schiff moment (NSM) and tensor–pseudotensor (T–PT) electron–nucleus (e–N) interaction as −6.3(5) × 10−17 S |e| cm/(|e| fm3) and −13(1) × 10−20 CT⟨σN⟩ |e| cm, respectively, for the NSM S, T–PT coupling coefficient CT and nuclear Pauli spinor σN. This is corroborated by analyzing the dipole polarizability value of 225Ra, which is obtained as 257(8) . Our EDM results, in combination with the measurement (2015 Phys. Rev. Lett. 114 233002), are about 8% and 28% improvements over the limits that were reported using the relativistic coupled-cluster theory for the NSM and T–PT e–N coupling coefficient, respectively. Further combining with the nuclear calculations, we infer limits on the EDM of neutron dn < 1.15 × 10−23 |e| cm, the EDM of proton dp < 1.1 × 10−22 |e| cm, the quantum chromodynamics parameter and the combined up- and down-quark chromo-EDMs . Though these bounds are not competitive at present with the current-best limits acquired from 199Hg atom, they can be bettered when the measurement of EDM in 225Ra improves by four orders.

Lattice calculation of electric dipole moments and form factors of the nucleon

We analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF) $F_3$ and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor $F_2$ due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the CP-violating quark chromo-EDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using background electric field that respects time translation invariance and boundary conditions, and find that it decidedly agrees with the new formula but not the old formula for $F_3$. Finally, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM.

Electric dipole moment ofRa225due toP- andT-violating weak interactions

We report rigorous calculations of electric dipole moment (EDM) in $^{225}$Ra due to parity and time-reversal violating tensor-pseudotensor (T-PT) and nuclear Schiff moment (NSM) interactions between the electrons and nucleus by employing the relativistic all order coupled-cluster (RCC) methods at various levels of approximation. The most accurate EDM ($d_A$) results are obtained as $d_A=-10.04\times 10^{-20} C_T <\sigma_n>|e|cm$ and $d_A^{NSM}=-6.79 \times 10^{-17} S (|e|fm^3)^{-1} |e|cm$ with $C_T$ and $S$ are the T-PT coupling constant and NSM respectively. Due to exhaustive treatment of the electron correlation effects in these calculations, the EDM results for the corresponding T-PT and NSM interactions reduce by about 45\% and 23\%, respectively, from the previously known values. Nonetheless they are still found to be 2-3 times larger than the $^{199}$Hg results. Validity of the RCC results are countenanced by comparing our calculations at the zeroth order Dirac-Fock method and all order random-phase approximation with the other groups. In view of the current experimental progress in the $^{225}$Ra EDM measurement, our high accuracy calculations are very useful to yield limits on $C_T$ and $S$ in this atom. Thusly, it is possible to realize more accurate limits on the electron-quark T-PT interaction and $\theta_{QCD}$ parameter of particle physics in future.

Rigorous limits on the hadronic and semileptonicCP-violating coupling constants from the electric dipole moment ofHg199

Relativistic many-body methods at different levels of approximations are employed to gain insights into the passage of the electron correlations from lower to higher levels in the accurate determination of the electric dipole polarizability ($\alpha_d$) and electric dipole moment (EDM) due to the electron-nucleus tensor-pseudotensor (T-PT) and nuclear Schiff moment (NSM) interactions of the $^{199}$Hg ground state. Moreover, plausible reasons for the differences in the previous calculations are pointed out. Comparison between the calculated and experimental results of $\alpha_d$ indicates that our EDM calculations are about 3\% accurate which in combination with the measured value of $^{199}$Hg EDM yield limits for the T-PT coupling constant $C_T < 2.31 \times 10^{-9}$ and the NSM $S<1.55 \times 10^{-12}|e|fm^3$. From this limit of $S$ and the latest nuclear structure calculation, we get improved limits for the strong CP violating parameter $\theta_{QCD} < 2.12 \times 10^{-10}$ and the combined up and down quark chromo-EDMs $(-0.004 \tilde{d}_u + 0.020 \tilde{d}_d) < 1.15 \times 10^{-27} |e| cm$.

Electric dipole moments of the fluorescent probes Prodan and Laurdan: experimental and theoretical evaluations.

Several experimental and theoretical approaches can be used for a comprehensive understanding of solvent effects on the electronic structure of solutes. In this review, we revisit the influence of solvents on the electronic structure of the fluorescent probes Prodan and Laurdan, focusing on their electric dipole moments. These biologically used probes were synthesized to be sensitive to the environment polarity. However, their solvent-dependent electronic structures are still a matter of discussion in the literature. The absorption and emission spectra of Prodan and Laurdan in different solvents indicate that the two probes have very similar electronic structures in both the ground and excited states. Theoretical calculations confirm that their electronic ground states are very much alike. In this review, we discuss the electric dipole moments of the ground and excited states calculated using the widely applied Lippert-Mataga equation, using both spherical and spheroid prolate cavities for the solute. The dimensions of the cavity were found to be crucial for the calculated dipole moments. These values are compared to those obtained by quantum mechanics calculations, considering Prodan in vacuum, in a polarizable continuum solvent, and using a hybrid quantum mechanics-molecular mechanics methodology. Based on the theoretical approaches it is evident that the Prodan dipole moment can change even in the absence of solute-solvent-specific interactions, which is not taken into consideration with the experimental Lippert-Mataga method. Moreover, in water, for electric dipole moment calculations, it is fundamental to consider hydrogen-bonded molecules.

Nuclear electric dipole moment of three-body systems

Background: The existence of the electric dipole moment (EDM) of stable nuclei would be a direct evidence of the time reversal invariance violation (TRIV). Therefore, its measurement could be considered as a complement to the search for neutron and atomic EDMs.Purpose: To clarify theoretical issues related to calculations of EDMs in many-body systems we calculated the EDMs of the simplest nuclei.Method: For calculations of three-nucleon systems EDMs we used TRIV potentials based on the meson exchange theory, as well as the ones derived by using effective field theories (EFT) with and without explicit pions. Nuclear wave functions were obtained by solving Faddeev equations in configuration space for the complete Hamiltonians comprising both TRIV and realistic strong interactions.Results: The expressions for EDMs of ${}^{3}\text{He}$ and ${}^{3}\text{H}$ are given in terms of meson exchange couplings and low energy constants of EFT potentials.Conclusions: The obtained results are compared with the previous calculations of ${}^{3}\text{He}$ EDM and with time reversal invariance violating effects in neutron-deuteron scattering. The model dependence on strong interactions is discussed.

Electric Dipole Moments of Light Nuclei and the Implications for CP Violation

A definitive measurement of an electric dipole moment (EDM) would likely imply new physics beyond the standard model. Although the standard model strong interaction term could theoretically produce an EDM of any size, that it is constrained by the current neutron EDM limit to be some 10 orders of magnitude smaller than 1 suggests that the electroweak sector and CP violation will be the source of a measurable EDM. The weak interaction standard model EDM is itself orders of magnitude smaller than contemporary experiments can measure. Direct measurement of the neutron EDM lies in the next decade; measurement of the proton EDM could well come first. A BNL proposal for an electrostatic storage ring measurement lies in the offing. Unless the EDM proves to be an isoscalar, one will need other measurements to separate the isoscalar, isovector, and isotensor components. Measurement of a nuclear EDM will be required: 2H, 3H, or 3He being the simplest nuclear systems. A storage ring measurement of the triton EDM could be accomplished in a manner analogous to that proposed for the proton. However, the deuteron EDM measurement offers certain advantages, even though the experiment would be more complex, involving electric and magnetic fields, than that required for the proton and triton. The COSY facility in the Forschungszentrum Juelich is almost an ideal facility to house such an experiment; one could also measure in the same ring the EDM for the proton and He. The deuteron is the one nucleus for which exact model calculations can easily be performed. We briefly explore the model dependence of deuteron EDM calculations. Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variations in the nucleon–nucleon interaction, including contemporary potential models, and we explore the dependence upon intermediate state multiple scattering in the 3P1 channel. We investigate the tensor force contribution to the model results and examine the effects of short-range repulsion that characterize realistic, contemporary potential models of the deuteron. Because one-pion exchange dominates the EDM calculation, separable potential model calculations appear to provide an adequate description of the deuteron EDM until such time as a measurement of better than 10 % is achieved.

Electric dipole moments of light nuclei from chiral effective field theory

We set up the framework for the calculation of electric dipole moments (EDMs) of light nuclei using the systematic expansion provided by chiral effective field theory (EFT). We take into account parity (P) and time-reversal (T) violation which, at the quark-gluon level, originates from the QCD vacuum angle and dimension-six operators capturing physics beyond the Standard Model. We argue that EDMs of light nuclei can be expressed in terms of six low-energy constants that appear in the P- and T-violating nuclear potential and electric current. As examples, we calculate the EDMs of the deuteron, the triton, and 3He in leading order in the EFT expansion.

Model dependence of theH2electric dipole moment

Background: Direct measurement of the electric dipole moment (EDM) of the neutron is in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the ${}^{3}$$P$${}_{1}$ channel, the latter being sensitive to the off-shell behavior of the ${}^{3}$$P$${}_{1}$ amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short-range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the $^{2}\mathrm{H}$ EDM until such time as a measurement better than $10%$ is obtained.

The2H Electric Dipole Moment in a Separable Potential Approach

Measurement of the electric dipole moment (EDM) of 2 H or of 3 He may well come prior to the cov- eted measurement of the neutron EDM. Exact model calculations for the deuteron are feasible, and we explore here the model dependence of such deuteron EDM calculations. We investigate in a separable potential approach the relationship of the full model calculation to the plane wave approximation, correct an error in an early poten- tial model result, and examine the tensor force aspects of the model results as well as the e ect of the short range repulsion found in the realistic, contemporary potential model calculations of Liu and Timmermans. We conclude that, because one-pion exchange dominates the EDM calculation, separable potential model calculations should provide an adequate picture of the 2 H EDM until better than 10% measurements are achieved.

Augmented Gaussian basis sets of triple and quadruple zeta valence quality for the atoms H and from Li to Ar: Applications in HF, MP2, and DFT calculations of molecular dipole moment and dipole (hyper)polarizability

Recently, segmented contracted basis sets of triple and quadruple zeta valence quality plus polarization functions for the atoms from H to Ar were reported. In this work, with the objective of having a better description of electron affinities, polarizabilities, and hydrogen bonding, each of these sets was augmented with diffuse (s and p symmetries) and polarization (p, d, f, and g symmetries) functions that were optimized for the anion at the Hartree–Fock (HF) and M ϕller–Plesset second-order (MP2) levels, respectively. This extends earlier work on segmented contracted double zeta valence basis set. In order to assess the quality of these sets, HF, MP2, and density functional theory calculations of electric dipole moment and static dipole polarizability and hyperpolarizability for a sample of molecules were carried out. The results are compared with theoretical and experimental values reported in the literature.

SYNOPSIS: SYNthesize and OPtimize System in Silico.

We present a de novo design program called SYNOPSIS, that includes a synthesis route for each generated molecule. SYNOPSIS designs novel molecules by starting from a database of available molecules and simulating organic synthesis steps. This way of generating molecules imposes synthetic accessibility on the molecules. In addition to a starting database, a fitness function is needed that calculates the value of a desired property for an arbitrary molecule. The values obtained from this function guide the design process in optimizing the molecules toward an optimal value of the calculated property. Two applications are described. The first uses an electric dipole moment calculation to generate molecules possessing a strong dipole moment. The second makes use of the three-dimensional structure of a viral enzyme in order to generate high affinity ligands. Twenty eight compounds designed with the program resulted in 18 synthesized and tested compounds, 10 of which showed HIV inhibitory activity in vitro.

Relaxation kinetics in virtual ferroelectrics: (K, Li)TaO3crystals

A method for the treatment of dielectric spectra thatallows calculation of electric dipole moments µ and off-centredisplacements δ of Li ions in (K, Li)TaO3 crystals is suggested and realized. These parametersdetermine characters of relaxation kinetics. The obtained estimations forµ and δ are confirmed by calculation with the Arrhenius law for themean relaxation time and are compared with the published data.

Electric dipole moment andCPviolation inB→Xsl+l−in supergravity models with nonuniversal gaugino masses

The constraints of electric dipole moments (EDMs) of the electron and neutron on parameter space in supergravity (SUGRA) models with nonuniversal gaugino masses are analyzed. It is shown that, with a light sparticle spectrum, a sufficient cancellation in the calculation of EDMs can happen for all phases of order 1 in the small $\mathrm{tan}\ensuremath{\beta}$ case and all phases but ${\ensuremath{\varphi}}_{\ensuremath{\mu}}$ $(|{\ensuremath{\varphi}}_{\ensuremath{\mu}}|\ensuremath{\lesssim}\ensuremath{\pi}/6)$ of order 1 in the large $\mathrm{tan}\ensuremath{\beta}$ case. This is in contrast with the case of MSUGRA in which, in the parameter space where cancellations among various SUSY contributions to EDMs happen, $|{\ensuremath{\varphi}}_{\ensuremath{\mu}}|$ must be less than $\ensuremath{\pi}/10$ for small $\mathrm{tan}\ensuremath{\beta}$ and $\mathcal{O}{(10}^{\ensuremath{-}2})$ for large $\mathrm{tan}\ensuremath{\beta}.$ Direct $\mathrm{CP}$ asymmetries and the T-odd normal polarization of the lepton in $\stackrel{\ensuremath{\rightarrow}}{B}{X}_{s}{l}^{+}{l}^{\ensuremath{-}}$ are investigated in these models. In the large $\mathrm{tan}\ensuremath{\beta}$ case, ${A}_{\mathrm{CP}}^{2}$ and ${P}_{N}$ for $l=\ensuremath{\mu}$ $(\ensuremath{\tau})$ can be enhanced by about a factor of 10 (10) and 10 (3), respectively, compared to those of MSUGRA.

Study on Underwater Electric Fields of a Dipole Moment in Shallow Water

We studied a method for estimating electric conductivity of the seabed which was necessary for the calculation of electric dipole moment of a boat from underwater electric field. Taking a model of a single electric dipole in a conducting medium with two boundary planes of the sea surface and the seabed, we calculated electric conductivity of the seabed using the measured underwater electric field of a direct current electric dipole. The measurement was conducted with three-axis electric field sensors set on the seabed at a depth of 16.7 m. The underwater electric fields of a tugboat were measured in the same manner as that for a direct current electric dipole. The conductivity of the seabed was calculated using the underwater electric field signature of the tugboat and the result agreed with that obtained from the direct current electric dipole.

Application of the coupled-cluster approach to the electric dipole moment of atoms and molecules due to parity and time-reversal violation.

In this paper we present a variant of Monkhorst's coupled-cluster-based linear-response approach designed for direct calculations of static properties of closed-shell many-fermion systems [Int. J. Quantum Chem Symp. 11, 421 (1977)]. All the required equations are derived in the framework of the coupled-cluster singles and doubles model. Although the approach has been developed with the calculation of electric-dipole moment of atoms and molecules due to parity- and time-reversal-violating interactions in mind, it is general enough to be applicable to other problems which require the presence of two one-electron perturbations.

The calculation of electric dipole moments from the polarization propagator. Theory and application

A method for computation of dipole moments from the polarization propagator is presented and applied to the H2O molecule. Using extended basis sets it is shown that the coupled cluster singles doubles polarization propagator approximation (CCSDPPA) reproduces the experimental dipole moment to a high degree of accuracy

Computer programme for calculation of electric dipole moments from measurements in solution

An ALGOL computer programme is described for the calculation of an electric dipole moment from measurements made on dilute solutions in a non-polar solvent.

Electric dipole moment calculations of molecules with sixteen valence electrons

(1972). Electric dipole moment calculations of molecules with sixteen valence electrons. Molecular Physics: Vol. 23, No. 6, pp. 1235-1239.