[QE-users] 答复: Question on CPMD

LEUNG Clarence liangxy123 at hotmail.com
Fri Jan 18 08:59:37 CET 2019


Dear Riccardo Bertossa,

Can CPMD run in NVT? Now I perform a system at 300K.
[cid:699ebdcb-eca4-4293-bb11-3ec1fa1e40db]

Ekinc is go up all the time:
[cid:8e608b01-ff5b-495c-854f-8a5da861e9c3]
ETOT and Econs go up all the time:
[cid:4cc11732-f5e7-4524-965a-575db70e4f00]
Econt is not a constant:
[cid:f77d6356-1df6-473c-a91a-0c0da4b153a0]

I have run 0K simulation to go to the ground state and give 300K, the input file is


&CONTROL
  calculation='cp' ,
  etot_conv_thr = 3.5D-6 ,
  forc_conv_thr = 4.0D-4 ,
  ekin_conv_thr = 1d-4 ,
  pseudo_dir='/home/qeuser/SSSP_acc_PBE' ,
  nstep = 70000 ,
  tstress = .false. ,
  tprnfor = .false. ,
  dt=2.067,
  isave = 100,
  iprint = 10,
  ndr = 56,
  ndw = 57,
  restart_mode = 'restart',
  verbosity = 'low' ,
/

&SYSTEM
  ibrav=14,
  celldm(1)=36.1187133640d0, celldm(2)=0.6119121863d0, celldm(3)=1.3079965678d0,
  celldm(4)=0.0000000000d0, celldm(5)=0.0000000000d0, celldm(6)=0.0000000000d0,
  nat=63,
  ntyp=2,
  ecutwfc=50,
  ecutrho=400,
  input_dft='PBE',
  vdw_corr = 'DFT-D3' ,
  nr1b = 16 ,
  nr2b = 16,
  nr3b = 16 ,
  nosym = .true. ,
/
&ELECTRONS
  emass = 400
  emass_cutoff = 2.50,
  electron_dynamics = 'verlet' ,
/
&IONS
  ion_dynamics  = 'verlet',
  tempw = 300 ,
  ion_temperature = 'nose' ,
  fnosep=6.6666,
  ion_radius(1)=1.0,
  ion_radius(2)=1.0,
/

ATOMIC_SPECIES
  C 12.010700d0 C_pbe_v1.2.uspp.F.UPF
  P  30.973800d0 P.pbe-n-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {crystal}
P        0.207062953   0.994563394   0.532135751
P        0.042823633   0.994796583   0.465770116
C        0.157559602   0.119473623   0.509211511
C        0.092142096   0.120398444   0.486938482
P        0.453113260   0.016237452   0.533698293
P        0.289980002   0.986689982   0.464529400
C        0.399646081   0.133053286   0.505994952
C        0.335858066   0.117232823   0.482213070
P        0.704320783   0.007706925   0.532982064
P        0.538824580   0.008408401   0.468045855
C        0.654037234   0.132822314   0.511474768
C        0.587848371   0.135094109   0.489114957
P        0.956731588  -0.000006745   0.532145072
P        0.791554157   0.002228032   0.466394516
C        0.907495292   0.125510515   0.509696521
C        0.841931621   0.126642797   0.487430517
P        0.208266817   0.243782922   0.529541853
P        0.043965854   0.246589308   0.464392818
C        0.158728245   0.369838186   0.509463992
C        0.093217169   0.370873210   0.486709312
P        0.424177849   0.286343852   0.516852430
P        0.290089532   0.244400471   0.459582516
C        0.349540011   0.348792825   0.487513040
P        0.705574516   0.255089554   0.532107492
P        0.542012221   0.260506971   0.464249905
C        0.656129286   0.380833823   0.512136142
C        0.590214180   0.381152001   0.490082742
P        0.957108151   0.250073183   0.531244245
P        0.792998637   0.251922321   0.464998669
C        0.907321789   0.375462368   0.510050868
C        0.841746979   0.376334296   0.487596817
P        0.208402877   0.492352243   0.532960869
P        0.043963546   0.496372026   0.465432581
C        0.160144417   0.618157610   0.509696507
C        0.094342113   0.619600026   0.487659242
P        0.471073678   0.513328655   0.548894023
P        0.309129724   0.486227608   0.474070256
C        0.414925399   0.629235003   0.523346545
C        0.350961159   0.616373438   0.499640968
P        0.705395802   0.505478539   0.534378721
P        0.537192856   0.506995560   0.474222102
C        0.656825419   0.631333460   0.511436510
C        0.590845794   0.632466501   0.490389008
P        0.956482750   0.499986748   0.532254831
P        0.791270143   0.501641183   0.466922839
C        0.906923580   0.625196225   0.510129362
C        0.841214140   0.626345388   0.488309739
P        0.207667541   0.743674910   0.533472131
P        0.043998636   0.744658734   0.465730512
C        0.158052412   0.868776604   0.510578825
C        0.092761413   0.869723388   0.488195850
P        0.461194613   0.761061943   0.539728957
P        0.299530254   0.737206731   0.471960596
C        0.407654987   0.881987587   0.515312903
C        0.343486860   0.870097791   0.492007540
P        0.706175574   0.757137135   0.532107627
P        0.539960743   0.756974729   0.469099032
C        0.655720285   0.882343139   0.510585276
C        0.589586421   0.883272199   0.489712695
P        0.956945276   0.749651294   0.531828394
P        0.791991567   0.752132650   0.465926241
C        0.907222485   0.875386768   0.509910655
C        0.841486983   0.876756958   0.488249976

K_POINTS {gamma}

Thanks very much.

LIANG Xiongyi
________________________________
发件人: users <users-bounces at lists.quantum-espresso.org> 代表 Riccardo Bertossa <rbertoss at sissa.it>
发送时间: 2019年1月18日 2:24
收件人: users at lists.quantum-espresso.org
主题: Re: [QE-users] Question on CPMD


dear LIANG,


when you run in the NVE you should have something like this:

[cid:part1.2BBB1DF7.418C4223 at sissa.it]

[cid:part2.309ED1CB.07CFEBCF at sissa.it]

if I am not wrong:

ekinc is the kinetic energy of the electrons

etot is the total potential energy (calculated with DFT)

econs is the energy that to make a good simulation you want to make as constant as possible, but it will oscillate because electrons have a mass and a kinetic energy, so it will never be constant.

econt is the constant of motion of the CP lagrangian, and this must always remain approximately constant, within the integration error of the verlet algorithm. If it is not constant your simulation is not good and you have to change some parameters.



best regards,

Riccardo Bertossa

SISSA


On 17/01/19 15:54, LEUNG Clarence wrote:
Dear QE users,

From CPMD, we can get    EKINC  ETOT   ENTHAL ECONS  and ECONT of the system. Which one is the total energy of the system?
ETOT? or Ekinc + Etot ? or Etot - Ekinc ?

Thanks.

LIANG Xiongyi
City University of Hong Kong



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