Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Hamiltonian Watson

There are two versions of MM. One, that we refer to as single-reference MM is based on the exact Watson Hamiltonian, which is the Hamiltonian in rectilinear... [Pg.59]

State calculations. With the extensions provided, the method can be applied to the full Watson Hamiltonian [51] for the vibrational problem. The efficiency of the method depends greatly on the nature of the anharmonic potential that represents couphng between different vibrational modes. In favorable cases, the latter can be represented as a low-order polynomial in the normal-mode displacements. When this is not the case, the computational effort increases rapidly. The Cl-VSCF is expected to scale as or worse with the number N of vibrational modes. The most favorable situation is obtained when only pairs of normal modes are coupled in the terms of the polynomial representation of the potential. The VSCF-Cl method was implemented in MULTIMODE [47,52], a code for anharmonic vibrational spectra that has been used extensively. MULTIMODE has been successfully applied to relatively large molecules such as benzene [53]. Applications to much larger systems could be difficult in view of the unfavorable scalability trend mentioned above. [Pg.171]

In our approach, we use the Watson Hamiltonian [14]. For the general case of nonlinear molecules this Hamiltonian is given (in atomic units) by... [Pg.252]

With the above approach we can combine the use of curvilinear normal coordinates with the Eckart frame. When we do so, the harmonic oscillator, rigid rotor, and, to lowest order, the Coriolis and centrifugal coupling contributions to H have exactly the same form as those found for the more commonly used Watson Hamiltonian (58). [Pg.158]

Along these lines an efficient protocol, called DEWE has been developed [155] which is based on the DVR of the Eckart-Watson Hamiltonians involving an exact inclusion of potentials expressed in an arbitrary set of coordinates. The DEWE procedure has been tested both for nonlinear (H2O, H3, and CH4) and linear (CO2, HCN, and HNC) molecules. [Pg.168]

Matyus, E., Czako, G., Sutcliffe, B.T. Csaszar, A.G. Vibrational energy levels with arbitrary potentials using the Eckart-Watson Hamiltonians and the discrete variable representation, J. Chem. Phys. 2007, in press. [Pg.176]

Her], Therefore, there are no odd-order terms in the effective Hamiltonian of Eq. (2.39), and it is possible to fit the, 4-lines to a standard Watson Hamiltonian. The PAM is mostly appropriate for high barrier cases. [Pg.24]

I + J = F and diagonalized. The A-reduced semirigid Watson Hamiltonian in the T representation is given by... [Pg.349]

The spectrum of the Watson Hamiltonian gives the rovibrational energy levels of the molecule under consideration. The resolution proceeds through the application of perturbation theory (Rayleigh-Schrodinger perturbation theory), which allows the partitioning of the Watson Hamiltonian into the rigid-rotor harmonic oscillator Hamiltonian H and a perturbation... [Pg.270]

Starting from the nuclear Hamiltonian defined in Eq. (10.2), the semirigid Watson Hamiltonian [208] gives the rotational-vibrational energy levels of the molecule under consideration and is expressed in dimensionless normal coordinates q as follows ... [Pg.262]


See other pages where Hamiltonian Watson is mentioned: [Pg.316]    [Pg.29]    [Pg.30]    [Pg.166]    [Pg.167]    [Pg.168]    [Pg.524]    [Pg.204]    [Pg.205]    [Pg.47]    [Pg.262]    [Pg.269]   
See also in sourсe #XX -- [ Pg.29 ]

See also in sourсe #XX -- [ Pg.262 , Pg.269 ]




SEARCH



Watson

© 2024 chempedia.info