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Mesoscopic Non-Equilibrium Thermodynamics: Application to Radiative Heat Exchange in Nanostructures 201 .1 .2 () (, ) (, ) st eq eq Ja T T ωρω ρω =− ⎡ ⎤ ⎣ ⎦ (21) where . 3 (,) (,) 2 eq NT T h ω ρω = (22) with h being the Planck constant and (,)NT ω the averaged number of photons in an elementary cell of volume 3 h of the phase-space given by the Planck distribution (Planck, 1959), 1 (,) . exp( / ) 1 B NT kT ω ω = −  (23) Moreover, the factor 2 in Eq. (22) comes from the polarization of photons. The stationary current (21) provides us with the flow of photons. Since each photon carries an amount of energy equal to ω  , the heat flow 12 Q follows from the sum of all the contributions as 12 () st QJd, ωω = ∫ p (24) where (/) p c ω =p  Ω , with p Ω being the unit vector in the direction of p . Therefore it follows that by taking /4ac = 12 1 2 () (, ) (, ) 16 p c Qdd TT, ωωθωθω π =Λ− ⎡⎤ ⎣⎦ ∫ Ω (25) with (,) (,)TNT θ ωωω =  being the mean energy of an oscillator and where 223 () / c ωωπ Λ= plays the role of the density of states. By performing the integral over all the frequencies and orientations in Eq. (25) we finally obtain the expression of the heat interchanged ( ) 44 12 1 2 QTT, σ =− (26) where 24 32 /60 B kc σπ =  is the Stefan constant. At equilibrium 12 TT = , therefore 12 0Q = . This expression reveals the existence of a stationary state (Saida, 2005) of the photon gas emitted at two different temperatures. Note that for a fluid in a temperature gradient, the heat current is linear in the temperature difference whereas in our case this linearity is not observed. Despite this fact, mesoscopic non-equilibrium thermodynamics is able to derive non-linear laws for the current. In addition, if we set 2 0T = in Eq. (26), we obtain the heat radiation law of a hot plate at a temperature 1 T in vacuum (Planck, 1959) 4 11 QT. σ = (27) 5. Near-field radiative heat exchange between two NPs In this section, we will apply our theory to study the radiative heat exchange between two NPs in the near-field approximation, i.e. when the distance d between these NPs satisfies both T d λ < and the near-field condition 24Rd R < <  , with R being the characteristic radius Thermodynamics 202 of the NPs. These NPs are thermalized at temperatures 12 TT = (see Fig. 3). In particular we will compute the thermal conductance and compare it with molecular simulations (Domingues et al., 2005). Fig. 3. Illustration of two interacting nanoparticles of characteristic radius R separated by a distance d of the order nm Since in the present case diffraction effects cannot be ignored D 1 and D 2 must be taken as frequency dependent quantities rather than constants and hence, Eq. (25) also applies, now with 223 12 () () () /DD c ωωωωπ Λ= . This density of states differs from the Debye approximation 223 / c ωπ related to purely vibration modes and is a characteristic of disordered systems which dynamics is mainly due to slow relaxing modes. Analogous to similar behaviour in glassy systems, we assume here that (Pérez-Madrid et al., 2009) 22 12 () () exp( )( ) R DD A B , ωω ωδωω =− (26) where the characteristic frequency A and the characteristic time B are two fitting parameters, and 2 / R cd ω π = is a resonance frequency. The heat conductance is defined as 12 12 2 12 0 12 () ( ) / lim TT Q GT R , TT ω π → = − (29) where 012 ()/2TTT=+ is the temperature corresponding to the stationary state of the system. Therefore, () () 2 22 0 22 12 0 2 0 / () exp . 4sinh/2 BR R B R RB kR kT GT A B ckT ωω ω πω ⎡ ⎤ = ⎢ ⎥ ⎢ ⎥ ⎣ ⎦   (30) In Fig. 4, we have represented the heat conductance as a function of the distance d between the NPs of different radii. This figure shows a significant enhancement of the heat conductance when d decreases until 2D , which, as has been shown in a previous work by means of electromagnetic calculations and using the fluctuation-dissipation theorem (Pérez- Madrid et al., 2008), is due to multipolar interactions. In more extreme conditions when the NPs come into contact to each other, a sharp fall occurs which can be interpreted as due to an intricate conglomerate of energy barriers inherent to the amorphous character of these NPs generated by the strong interaction. In these last circumstances the multipolar expansion is no longer valid. Mesoscopic Non-Equilibrium Thermodynamics: Application to Radiative Heat Exchange in Nanostructures 203 Fig. 4. Thermal conductance G 12 vs. distance d reproducing the molecular dynamics data obtained by (Domingues et al., 2005). The grey points represent the conductance when the NPs with effective radius R = 0.72, 1.10, and 1.79 nm are in contact. The lines show the analytical result obtained from Eq. (30) by adjusting A and B to the simulation data 6. Conclusions The classical way to study non-equilibrium mesoscopic systems is to use microscopic theories and proceed with a coarse-graining procedure to eliminate the degrees of freedom that are not relevant to the mesoscopic scale. Such microscopic theories are fundamental to understand how the macroscopic and mesoscopic behaviours of the system arise from the microscopic dynamics. However, these theories frequently involve specialized mathematical methods that prevent them from being generally applicable to complex systems; and more importantly, they use much detailed information that is lost during the coarse-graining procedure and that is actually not needed to understand the general properties of the mesoscopic dynamics. The mesoscopic non-equilibrium thermodynamics theory we have presented here starts from mesoscopic equilibrium behaviour and adds all the dynamic details compatible with the second principle of thermodynamics and with the conservation laws and symmetries inherent to the system. Thus, given the equilibrium statistical thermodynamics of a system, it is a straightforward process to obtain Fokker-Planck equations for its dynamics. The dynamics is characterized by a few phenomenological coefficients, which can be obtained for the particular situation of interest from experiments or from microscopic theories and describes not only the deterministic properties but also their fluctuations. Mesoscopic non-equilibrium thermodynamics has been applied to a broad variety of situations, such as activated processes in the non-linear regime, transport in the presence of entropic forces and inertial effects in diffusion. Transport at short time and length scales exhibits peculiar characteristics. One of them is the fact that transport coefficients are no longer constant but depend on the wave vector and frequency. This dependence is due to the existence of inertial effects at such scales as a consequence of microscopic conservation Thermodynamics 204 law. The way in which these inertial effects can be considered within a non-equilibrium thermodynamics scheme has been shown in Rubí & Pérez-Madrid, 1998. We have presented the application of the theory to the case of radiative heat exchange, a process frequently found at the nanoscale. The obtention of the non-equilibrium Stefan- Boltzmann law for a non-equilibrium photon gas and the derivation of heat conductance between two NPs confirm the usefulness of the theory in the study of thermal effects in nanosystems. 7. References Callen, H. (1985). Thermodynamics and an introduction to thermostatistics. New York: John Wiley and Sons. Callen, H.B. & Welton, T.A. (1951). Irreversibility and Generalized Noise. Phys. Rev. , 83, 34-40. Carminati, R. et al. (2006). Radiative and non-radiative decay of a single molecule close to a metallic NP. Opt. Commun. , 261, 368-375. de Groot & Mazur (1984). Non-Equilibrium Thermodynamics. New York: Dover. De Wilde, Y. et al. (2006). Thermal radiation scanning tunnelling microscopy. Nature, 444, 740-743. Domingues G. et al. (2005). Heat Transfer between Two NPs Through Near Field Interaction. Phys. Rev. Lett., 94, 085901. Förster, T. (1948). Zwischenmolekulare Energiewanderung und Fluoreszenz. Annalen der Physik, 55-75. Frauenfelder H. et al. (1991). Science, 254, 1598-1603. Hess, S. & Köhler, W. (1980). Formeln zur Tensor-Rechnung. Erlangen: Palm & Enke. Joulain, K. et al. (2005). Surface electromagnetic waves thermally excited: Radiative heat transfer, coherence properties and Casimir forces revisited in the near field. Surf. Sci. Rep. , 57, 59-112. Landau, L.D. & Lifshitz, E.M. (1980). Staistical Physics (Vol. 5). Oxford: Pergamon. Narayanaswamy, A. & Chen, G. (2003). Surface modes for near field thermophotovoltaics. Appl. Phys. Lett. , 82, 3544-3546. Pagonabarraga, I. et al. (1997). Fluctuating hydrodynamics approach to chemical reactions. Physica A , 205-219. Peng, H. et al. (2010). Luminiscent Europium (III) NPs for Sensing and Imaging of Temperature in the Physiological Range. Adv. Mater. , 22, 716-719. Pérez-Madrid, A. et al. (2009). Heat exchange between two interacting NPs beyond the fluctuation-dissipation regime. Phys. Rev. Lett. , 103, 048301. Pérez-Madrid, A. et al. (2008). Heat transfer between NPs: Thermal conductance for near- field interactions. Phys. Rev. B , 77, 155417. Planck, M. (1959). The Theory of Heat Radiation. New York: Dover. Reguera, D. et al. (2006). The Mesoscopic Dynamics of Thermodynamic Systems. J. Phys. Chem. B, 109, 21502-21515. Rousseau, E. et al. (2009). Radiative heat transfer at the nanoscale. Nature photonics , 3, 514-517. Rubí J.M. & Pérez-Vicente C. (1997). Complex Behaviour of Glassy Systems. Berlin: Springer. Rubí, J.M. & Pérez-Madrid, A. (1999). Inertial effetcs in Non-equillibrium thermodynamics. Physica A, 492-502. Saida, H. (2005). Two-temperature steady-state thermodynamics for a radiation field. Physica A, 356, 481–508. 11 Extension of Classical Thermodynamics to Nonequilibrium Polarization Li Xiang-Yuan, Zhu Quan, He Fu-Cheng and Fu Ke-Xiang College of Chemical Engineering, Sichuan University Chengdu 610065 P. R. China 1. Introduction Thermodynamics concerns two kinds of states, the equilibrium ones (classical thermodynamics) and the nonequilibrium ones (nonequilibrium thermodynamics). The classical thermodynamics is an extremely important theory for macroscopic properties of systems in equilibrium, but it can not be fully isolated from nonequilibrium states and irreversible processes. Therefore, within the framework of classical thermodynamics, it is significant to explore a new method to solve the questions in the nonequilibrium state. Furthermore, this treatment should be helpful for getting deep comprehension and new applications of classical thermodynamics. For an irreversible process, thermodynamics often takes the assumption of local equilibrium, which divides the whole system into a number of macroscopic subsystems. If all the subsystems stand at equilibrium or quasi-equilibrium states, the thermodynamic functions for a nonequilibrium system can be obtained by some reasonable treatments. However, the concept of local equilibrium lacks the theoretical basis and the expressions of thermodynamic functions are excessively complicated, so it is hard to be used in practice. Leontovich[ 1 ] once introduced a constrained equilibrium approach to treat nonequilibrium states within the framework of classical thermodynamics, which essentially maps a nonequilibrium state to a constrained equilibrium one by imposing an external field. In other words, the definition of thermodynamic functions in classical thermodynamics is firstly used in constrained equilibrium state, and the following step is how to extend this definition to the corresponding nonequilibrium state. This theoretical treatment is feasible in principle, but has not been paid much attention to yet. This situation is possibly resulted from the oversimplified descriptions of the Leontovich’s approach in literature and the lack of practical demands. Hence on the basis of detailed analysis of additional external parameters, we derive a more general thermodynamic formula, and apply it to the case of nonequilibrium polarization. The results show that the nonequilibrium solvation energy in the continuous medium can be obtained by imposing an appropriate external electric field, which drives the nonequilibrium state to a constrained equilibrium one meanwhile keeps the charge distribution and polarization of medium fixed. Thermodynamics 206 2. The equilibrium and nonequilibrium systems 2.1 Description of state The state of a thermodynamic system can be described by its macroscopic properties under certain ambient conditions, and these macroscopic properties are called as state parameters. The state parameters should be divided into two kinds, i.e. external and internal ones. The state parameters determined by the position of the object in the ambient are the external parameters, and those parameters, which are related to the thermal motion of the particles constituting the system, are referred to the internal parameters. Consider a simple case that the system is the gas in a vessel, and the walls of the vessel are the object in the ambient. The volume of the gas is the external parameter because it concerns only the position of the vessel walls. Meanwhile, the pressure of the gas is the internal parameter since it concerns not only the position of the vessel walls but also the thermal motion of gas molecules. All objects interacting with the system should be considered as the ambient. However, we may take some objects as one part of a new system. Therefore, the distinction between external and internal parameters is not absolute, and it depends on the partition of the system and ambient. Note that whatever the division between system and ambient, the system may do work to ambient only with the change of some external parameters. Based on the thermodynamic equilibrium theory, the thermal homogeneous system in an equilibrium state can be determined by a set of external parameters {} i a and an internal parameter T , where T is the temperature of the system. In an equilibrium state, there exists the caloric equation of state, (,) i UUaT = , where U is the energy of the system,system capacitysystem capacity so we can choose one of T and U as the internal parameter of the system. However, for a nonequilibrium state under the same external conditions, besides a set of external parameters {} i a and an internal parameter U (or T ), some additional internal parameters should be invoked to characterize the nonequilibrium state of an thermal homogeneous system. It should be noted that those additional internal parameters are time dependent. 2.2 Basic equations in thermodynamic equilibrium In classical thermodynamics, the basic equation of thermodynamic functions is dd d ii i TS U A a=+ ∑ (2.1) where S , U and T represent the entropy, energy and the temperature (Kelvin) of the equilibrium system respectively. {} i a stand for a set of external parameters, and i A is a generalized force which conjugates with i a . The above equation shows that the entropy of the system is a function of a set of external parameters {} i a and an internal parameter U , which are just the state parameters that can be used to describe a thermal homogeneous system in an equilibrium state. So the above equation can merely be integrated along a quasistatic path. Actually, dTS is the heat r Q δ absorbed by the system in the infinitesimal change along a quasistatic path. dU is the energy and d ii Aa is the element work done by the system when external parameter i a changes. It should be noticed that the positions of any pair of i A and i a can interconvert through Legendre transformation. We consider a system in which the gas is enclosed in a cylinder Extension of Classical Thermodynamics to Nonequilibrium Polarization 207 with constant temperature, there will be only one external parameter, i.e. the gas volume V . The corresponding generalized force is the gas pressure p , so eq. (2.1) can be simplified as dd dTS U pV = + (2.2) It shows that (,)SSUV= . If we define HUpV = + , eq. (2.2) may be rewritten as dd( )dd dTS U pV Vp H Vp=+−=− (2.3) Thus we have (,)SSHp = . If we choose the gas pressure p as the external parameter, then V should be the conjugated generalized force, and the negative sign in eq. (2.3) implies that the work done by the system is positive as the pressure decreases. Furthermore, the energy U in eq. (2.2) has been changed with the relation of UpVH + = in eq. (2.3), in which H stands for the enthalpy of the gas. 2.3 Nonequilibrium state and constrained equilibrium state It is a difficult task to efficiently extend the thermodynamic functions defined in the classical thermodynamics to the nonequilibrium state. At present, one feasible way is the method proposed by Leontovich. The key of Leontovich’s approach is to transform the nonequilibrium state to a constrained equilibrium one by imposing some additional external fields. Although the constrained equilibrium state is different from the nonequilibrium state, it retains the significant features of the nonequilibrium state. In other words, the constraint only freezes the time-dependent internal parameters of the nonequilibrium state, without doing any damage to the system. So the constrained equilibrium becomes the nonequilibrium state immediately after the additional external fields are removed quickly. The introduction and removal of the additional external fields should be extremely fast so that the characteristic parameters of the system have no time to vary, which provides a way to obtain the thermodynamic functions of nonequilibrium state from that of the constrained equilibrium state. 2.4 Extension of classical thermodynamics Based on the relation between the constrained equilibrium state and the nonequilibrium one, the general idea of extending classical thermodynamics to nonequilibrium systems can be summarized as follows: 1. By imposing suitable external fields, the nonequilibrium state of a system can be transformed into a constrained equilibrium state so as to freeze the time-dependent internal parameters of the nonequilibrium state. 2. The change of a thermodynamic function between a constrained equilibrium state and another equilibrium (or constrained equilibrium) state can be calculated simply by means of classical thermodynamics. 3. The additional external fields can be suddenly removed without friction from the constrained equilibrium system so as to recover the true nonequilibrium state, which will further relax irreversibly to the eventual equilibrium state. Leontovich defined the entropy of the nonequilibrium state by the constrained equilibrium. In other words, entropy of the constrained equilibrium and that of the nonequilibrium exactly after the fast removal of the external field should be thought the same. Thermodynamics 208 According to the approach mentioned above, we may perform thermodynamic calculations involving nonequilibrium states within the framework of classical thermodynamics. 3. Entropy and free energy of nonequilibrium state 3.1 Energy of nonequilibrium states For the clarity, only thermal homogeneous systems are considered. The conclusions drawn from the thermal homogeneous systems can be extended to thermal inhomogeneous ones as long as they consist of finite isothermal parts [1] . As a thermal homogeneous system is in a constrained equilibrium state, the external parameters of the system should be divided into three kinds. The first kind includes those original external parameters {} i a , and they have the conjugate generalized forces {} i A . The second kind includes the additional external parameters {} k x , which are totally different from the original ones. Correspondingly, the generalized forces {} k ξ conjugate with {} k x , where k ξ is the internal parameter originating from the nonequilibrium state. The third kind is a new set of external parameters {'} l a , which relate to some of the original external fields and the additional external parameters, i.e., '' lll aax = + (3.1) where l a and ' l x stand for the original external parameter and the additional external parameter, respectively. Supposing a generalized force ' l A conjugates with the external parameter ' l a , the basic thermodynamic equation for a constrained equilibrium state can be expressed by considering all the three kinds of external parameters, {} i a , {} i x , and {'} l a , i.e. ** dd d d 'd' ii k k l l ikl TS U A a x A a ξ =+ + + ∑ ∑∑ (3.2) where * S and * U stand for entropy and energy of the constrained nonequilibrium state, respectively, and other terms are the work done by the system due to the changes of three kinds of external parameters. Because the introduction and removal of additional external fields are so fast that the internal parameters k ξ and ' l A may remain invariant. The transformation from the constrained equilibrium state to the nonequilibrium state can be regarded adiabatic. Beginning with this constrained equilibrium, a fast removal of the constraining forces {} k x from the system then yields the true nonequilibrium state. By this very construction, the constrained equilibrium and the nonequilibrium have the same internal variables. In particular, the nonequilibrium entropy non S is equal to that of the constrained equilibrium [1] non * SS = (3.3) The energy change of the system in the fast (adiabatic) process is given as follows non * UU U W Δ =−=− (3.4) where non U denotes the energies of the true nonequilibrium, and W is the work done by the system during the non-quasistatic removal of the constraining forces, i.e., Extension of Classical Thermodynamics to Nonequilibrium Polarization 209 0 non ' *d'd''' l kll a kk l l kk ll xax kl kl UUW x A a x Ax ξξ + −=−=− − = + ∑∑ ∑∑ ∫∫ (3.5) where kk k x ξ ∑ and ' ' ll l Ax ∑ are work done by getting rid of the second and the third kinds of additional external fields quickly. Eq. (3.5) is just the relation between the energy of the nonequilibrium state and that of the constrained equilibrium state. If '0 l A = , eq. (3.5) is reduced to the Leontovich form, i.e., (Eq.3.5 of ref 1) * kk k UU x ξ =+ ∑ (3.6) '0 l A = indicates that the constraining forces {} k ξ are new internal parameters which do not exist in the original constrained equilibrium state. This means that eq. (3.5) is an extension of Leontovich’s form of eq. (3.6). If one notes that k ξ and ' k A remains invariant during the fast removal of their conjugate parameters, the energy change by eq. (3.5) becomes straightforward. 3.2 Free energies of the constrained equilibrium and nonequilibrium states The free energy of the constrained equilibrium state * F is defined as ** * FUTS=− (3.7) Differentiating on the both sides of eq. (3.7) by substituting of eq. (3.2), we have ** dd d d 'd' ii k k l l ikl FST Aa x Aa ξ =− − − − ∑ ∑∑ (3.8) The free energy of the nonequilibrium state non F is defined as non non non FUTS=− (3.9) Subtracting eq. (3.7) from eq. (3.9), with noticing eq. (3.5), we have non *'' kk l l kl FF x Ax ξ −= + ∑ ∑ (3.10) From the above equation, non F can be obtained from * F . A particularly noteworthy point should be that ' l A and ' l x are not a pair of conjugates, so the sum ' ' ll l Ax ∑ in eq. (3.10) does not satisfy the conditions of a state function. This leads to that the total differential of non F does not exist. Adding the sum ' ll l Aa ∑ to both sides of eq. (3.10), the total differential can be obtained as non non d( ' ) d d d 'd ' ll i i k k l l likl FAaSTAax aA ξ +=−−++ ∑ ∑∑∑ (3.11) If the third kind of external parameters do not exist, i.e., 0 l a = and '0 l x = , hence '0 l a = , eq. (3.11) is identical with that given by Leontovich [1] . Eq. (3.11) shows that if there are external Thermodynamics 210 parameters of the third kind, the nonequilibrium free energy non F which comes from the free energy * F of the constrained state does not possess a total differential. This is a new conclusion. However, it will not impede that one may use eq. (3.11) to obtain non F , because with this method one can transform the nonequilibrium state into a constrained equilibrium state, which can be called as state-to-state treatment. This treatment does not involve the state change with respect to time, so it can realize the extension of classical thermodynamics to nonequilibrium systems. 4. Nonequilibrium polarization and solvent reorganization energy In the previous sections, the constrained equilibrium concept in thermodynamics, which can be adopted to account for the true nonequilibrium state, is introduced in detail. In this section, we will use this method to handle the nonequilibrium polarization in solution and consequently to achieve a new expression for the solvation free energy. In this kind of nonequilibrium states, only a portion of the solvent polarization reaches equilibrium with the solute charge distribution while the other portion can not equilibrate with the solute charge distribution. Therefore, only when the solvent polarization can be partitioned in a proper way, the constrained equilibrium state can be constructed and mapped to the true nonequilibrium state. 4.1 Inertial and dynamic polarization of solvent Theoretical evaluations of solvent effects in continuum media have attracted great attentions in the last decades. In this context, explicit solvent methods that intend to account for the microscopic structure of solvent molecules are most advanced. However, such methods have not yet been mature for general purposes. Continuum models that can handle properly long range electrostatic interactions are thus far still playing the major role. Most continuum models are concerned with equilibrium solvation. Any process that takes place on a sufficiently long timescale may legitimately be thought of as equilibration with respect to solvation. Yet, many processes such as electron transfer and photoabsorption and emission in solution are intimately related to the so-called nonequilibrium solvation phenomena. The central question is how to apply continuum models to such ultra fast processes. Starting from the equilibrium solvation state, the total solvent polarization is in equilibrium with the solute electric field. However, when the solute charge distribution experiences a sudden change, for example, electron transfer or light absorption/emission, the nonequilibrium polarization emerges. Furthermore, the portion of solvent polarization with fast response speed can adjust to reach the equilibrium with the new solute charge distribution, but the other slow portion still keeps the value as in the previous equilibrium state. Therefore, in order to correctly describe the nonequilibrium solvation state, it is important and necessary to divide the total solvent polarization in a proper way. At present, there are mainly two kinds of partition method for the solvent polarization. The first one was proposed by Marcus [2] in 1956, in which the solvent polarization is divided into orientational and electronic polarization. The other one, suggested by Pekar [3] , considers that the solvent polarization is composed by inertial and dynamic polarization. The first partition method of electronic and orientational polarization is established based on the relationship between the solvent polarization and the total electric field in the solute- solvent system. We consider an electron transfer (or light absorption/emission) in solution. [...]... ( D ⋅ E − E c ⋅ E c )dV 8 ∫ 1 1 = ( E ⋅ E c − D ⋅ E c )dV + (E + E c ) ⋅ (D − E c )dV 88 ∫ Fsol = (4.17) We note that E = −∇Φ , E c = −∇ψ c (4. 18) where Φ is the total electric potential produced and ψ c is the electric potential by the solute (free) charge in vacuum With eq.(4. 18) , the last term in the second equality of eq.(4.17) becomes − 1 ∇(Φ + ψ c ) ⋅ (D − E c )dV 8 ∫ (4.19) The volume... ∇(Φ + ψ c ) ⋅ (D − E c )dV 8 ∫ (4.19) The volume integral (4.19) can be change to the following form by integration by parts: 1 ( Φ + ψ c )∇ ⋅ (D − E c )dV = 0 8 ∫ (4.20) Extension of Classical Thermodynamics to Nonequilibrium Polarization 215 Thus eq.(4.17) can be rewritten as[7 ,8] Fsol = − 1 P ⋅ E cdV 2∫ (4.21) We consider our nonequilibrium polarization case For the solvent system in the constrained... yet completely irrelevant From this reference, the electrostatic free energy of nonequilibrium solvation can directly be obtained in strict accordance with the principle of thermodynamics It is also shown that the long lasting 2 28 Thermodynamics problem that the solvent reorganization energy is always overestimated by the previous continuum models is solved in a natural manner It is believed that the... equal to the dynamic polarization in equilibrium state “2” 4.2 Constrained equilibrium by external field and solvation energy in nonequilibrium state Based on the inertial-dynamic polarization partition, the thermodynamics method introduced in the previous sections can be adopted to obtain the solvation energy in nonequilibrium state, which is a critical problem to illustrate the ultra-fast dynamical... energy is supposed invariant here Therefore, the most important contribution to the solvation energy change from equilibrium to nonequilibrium Extension of Classical Thermodynamics to Nonequilibrium Polarization 213 is the electrostatic part, and the electrostatic solvation energy, which measures the free energy change of the medium, simplified as solvation energy in the following paragraphs, is the... (4.5) The second partition method for the polarization is based on the equilibrium relationship between the dynamic polarization and electric field Assuming that the solvent only has the optical dielectric constant ε op , the dynamic electric field strength and the polarization in equilibrium state “1” and “2” can be expressed as P1,dy = χ opE 1,dy , (4.6) P2,dy = χ opE 2,dy (4.7) 212 Thermodynamics. .. defined as P1,in = P1eq − P1,dy , P2,in = P2eq − P2,dy (4 .8) where the subscripts “dy” and “in” stand for the quantities due to the dynamic and inertial polarizations In a nonequilibrium state, the inertial polarization will be regarded invariant, and hence the total polarization is decomposed to P2non = P1,in + P2,dy (4.9) With the dynamic-inertial partition, the nonequilibrium polarization is of the following... shift for the absorption spectrum can be defined as the solvation energy difference between nonequilibrium excited state “2” and equilibrium ground state “1”, i.e eq non Δhν ab = F2,sol − F1,sol (4.35) 2 18 Thermodynamics Correspondingly, for the inversed process, namely, emission (or fluorescence) spectrum, the spectral shift can be expressed as eq non Δhν em = F1,sol − F2,sol (4.36) According to the definitions... (4.46) With the similar treatment, the total polarization potential at the center of sphere A is ΔϕA,dy = −( Δq Δq 1 − )( − 1) rA d ε op (4.47) 220 Thermodynamics For the solvent with dielectric constant ε s , we have ΔϕD,eq = ( Δq Δq 1 − )( − 1) rD d εs (4. 48) Δq Δq 1 − )( − 1) rA d εs (4.49) ΔϕA,eq = −( With the zeroth approximation of multipole expansion for the solute charge distribution, the external... Q1 ) (ε s − 1)ε op (4. 58) Thus eqs (4.39) and (4.41) can be simplified as 1 2 λs = qex ( Δϕeq − Δϕdy ) (4.59) 1 eq eq Δhν ab = λs + (Q2ϕ2 − Q1ϕ1 ) 2 (4.60) 1 ε op − ε s Q − Q1 1 − ε s 1 − ε op 1 Q 1 Q 1 (Q2 − Q1 ) 2 ( ) + [Q2 2 ( − 1) − Q1 1 ( − 1)] = − 2 (ε s − 1)ε op a 2 a εs a εs εs ε op Further we have the form of the spectral shift in the vertical ionization of the charged particle, Δhν ab = (ε . Non-equillibrium thermodynamics. Physica A, 492-502. Saida, H. (2005). Two-temperature steady-state thermodynamics for a radiation field. Physica A, 356, 481 –5 08. 11 Extension of Classical Thermodynamics. Introduction Thermodynamics concerns two kinds of states, the equilibrium ones (classical thermodynamics) and the nonequilibrium ones (nonequilibrium thermodynamics) . The classical thermodynamics. polarization as sol c c cc c c 1 ()d 8 11 ()d()()d 88 FV VV π ππ =⋅−⋅ =⋅−⋅++⋅− ∫ ∫∫ DEEE EE DE E E D E (4.17) We note that = −∇ΦE , cc ψ =−∇E (4. 18) where Φ is the total electric potential

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