ISSN:0010-3640    

DOI:10.1002/cpa.3160420802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractIn a recent paper, we presented a new computational method for molecular dynamics which uses the Backward‐Euler scheme to solve the classical Langevin dynamics equations. Parameters for the simulation include a target temperatureT, a time step Δt, and a cutoff frequency ωc.We showed for a harmonic oscillator system that the cutoff frequency can be set as ωc=kT/hin order to mimic quantum‐mechanical behavior. We now continue this investigation for a nonlinear case: a diatomic molecule governed by a Morse bond potential. Since approximate quantum‐mechanical energy levels are explicitly known for this model, a comparison of energies can be made with molecular dynamics results. By performing dynamics runs for a wide range of temperatures and calculating mean energies, we find a very good agreement between these energies and quantum mechanical predictions. Vibrational excitation begins at temperatures around 800 K, and for higher temperatures both energy curves (molecular dynamics and quantum mechanics) approach the classical prediction of 7/2kTenergy per molecule. Future investigations will focus on more general nonlinear potential functions employed in force fields of nucleic acids and

ISSN:0010-3640    

DOI:10.1002/cpa.3160420807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe consider solutions of the Boltzmann equation, in ad‐dimensional torus,d= 2, 3,For macroscopic times τ =t/ϵN, ϵ « 1,t≧ 0, when the space variations are on a macroscopic scalex= ϵN−1r, N≧ 2,xin the unit torus. Letu(x, t)be, fort≦t0, a smooth solution of the incompressible Navier Stokes equations (INS) forN= 2 and of the Incompressible Euler equation (IE) forN>2.We prove that (*) has solutions fort≦t0which are close, toO(ϵ2) in a suitable norm, to the local Maxwellian [p/(2πT)d/2]exp{−[v− ϵu(x,t)]2/2T} with constant densitypand temperatureT. This is a particular case, defined by the choice of initial values of the macroscopic variables, of a class of such solutions in which the macroscopic variables satisfy more general hydrodynamical equations. ForN≧ 3 these equations correspond to variable density IE while forN= 2 they involve higher‐order

ISSN:0010-3640    

DOI:10.1002/cpa.3160420810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0010-3640    

DOI:10.1002/cpa.3160420811

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY