Dear Marty, Thx again.Now I am famaliar with the atomic units---'Ha'. since it shows: *[yangxu@WimaxServer 20110113-10]$ /opt/siesta-3.0-rc2/bin/**optical * * Do you want to include a Drude term?* * This is typically needed for metals* * if yes: enter 1, if no: enter 0* *1* * We need an empirical relaxation time* * Enter the invers in Ha units* * * Let's talk about Au as an example. As you implied, *So a relaxation time of 3e-14 seconds (which is the value for gold at 300K) * *works out to be* *0.137856 eV* *or * *0.005066 Ha* * * what should I enter,0.005066 or 197.394(ie 1/0.005066)?
I am looking forward from you! best wishes! xiaolin, from ZJU 2011/1/15 Marty Blaber <[email protected]> > Hi Lin Xiao, > > You are right, it means hartree atomic units. Below is an explanation of > how to get from relaxation time in seconds to Ha. > > The Drude dielectric function looks like: > > epsilon = 1 - wp^2 / [ w ( w + i/tau ) ] > > Where tau is the relaxation time (average time between collisions of an > electron with impurities/defects/ions) > Usually the relaxation time is specified in seconds. > > Siesta uses the damping rate or scattering rate (inverse relaxation time): > gamma = 1 / tau > where gamma is in Hartree units. > > To convert from inverse seconds to hartrees: > > electron_volts = planck/ ( elec_charge * time ) > = 6.626e-34 / ( 1.606e-19 * t ) > = J s / ( J/eV * s) > = eV > > then divide by 27.2114 to get Hartrees. > > So a relaxation time of 3e-14 seconds (which is the value for gold at 300K) > works out to be > 0.137856 eV > or > 0.005066 Ha > > Cheers, > Marty > > > On 14 January 2011 08:35, lin xiao <[email protected]> wrote: > > Dear Marty, > > There is a small problem remaining. > > When i do as you said, > > [yangxu@WimaxServer 20110113-10]$ /opt/siesta-3.0-rc2/bin/optical > > Do you want to include a Drude term? > > This is typically needed for metals > > if yes: enter 1, if no: enter 0 > > 1 > > We need an empirical relaxation time > > Enter the invers in Ha units > > here,what is the meaning of "Ha units"?Does 'Ha units' means HATREE,ie > > atomic units,or something else? > > BEST WISHES! > > xiaolin, from ZJU > > 2011/1/14 lin xiao <[email protected]> > >> > >> Dear Marty, > >> I appreciate your explaining.It really helps a lot. > >> Thx again. > >> xiaolin, from zju > >> > >> 2011/1/14 Marty Blaber <[email protected]> > >>> > >>> Hi Lin Xiao, > >>> > >>> At the command line, you must type only: > >>> > >>> optical > >>> > >>> without the <e2.dat > >>> the < operator has the effect of pasting the file into the standard > >>> input stream of the program. This is where you were supposed to type > >>> in the "1". > >>> Now, optical will ask the question: > >>> > Do you want to include a Drude term? > >>> > This is typically needed for metals > >>> > if yes: enter 1, if no: enter 0 > >>> and you may enter 1. > >>> > >>> Cheers, > >>> Marty > >>> > >>> > >>> > >>> On 12 January 2011 21:52, lin xiao <[email protected]> wrote: > >>> > Dears, > >>> > I'm using the optical model of siesta to calculate graphene.Here is a > >>> > question: > >>> > [guozhendong@yangxu-433 20110112-2]$ /opt/siesta-3.0-rc2/bin/optical > >>> > <e2.dat > >>> > Do you want to include a Drude term? > >>> > This is typically needed for metals > >>> > if yes: enter 1, if no: enter 0 > >>> > [guozhendong@yangxu-433 20110112-2]$ > >>> > Then whatever i enter,for instance 1 ,the system answer is: > >>> > 1: Command not found. > >>> > What should i do if i want to include the Drude term? > >>> > Thx! > >>> > > >>> > > >> > > > > > >
