Initial velocities in MD run
Posted: Mon Jun 11, 2012 5:22 pm
Dear All,
1) During MD, when initial velocities are not provided, it calculates by itself using Maxwell boltzmann distribution. Is there anyway that we can see these velocities.
2) When the velocities are manually supplied in the POSCAR, what is the format. Can anyone provide example.
I used the below format for a system with 13 atoms.
Is this right.
O C W
1.00000000000000
30.0000000000000000 0.0000000000000000 0.0000000000000080
0.0000000000000000 30.0000000000000000 0.0000000000000050
0.0000000000000070 0.0000000000000070 30.0000000000000000
O C W
6 6 1
Direct
0.60803984 0.5 0.5
0.39196016 0.5 0.5
0.5 0.60803984 0.5
0.5 0.39196016 0.5
0.5 0.5 0.60803984
0.5 0.5 0.39196016
0.5 0.56924576 0.5
0.5 0.43075424 0.5
0.5 0.5 0.56924576
0.5 0.5 0.43075424
0.56924576 0.5 0.5
0.43075424 0.5 0.5
0.5 0.5 0.5
-0.0009500646959681771 0.00015729464158412024 -0.00019558904034565843
0.0017851853040324558 -0.00001746089867484154 0.00013806633151759268
0.00002635753390306727 -0.000956833128546547 -0.00014128509974974053
0.0001606130741621412 0.0001002168714552331 -0.00006668760907879347
-0.00045308701003618946 -0.00006460938320967939 0.0045900386455848905
-0.00019334238189980745 -0.00006675687388040273 -0.002098461354414318
0.0003433713484046032 0.0004165668714537551 -0.0004449224385452537
-0.000409750740340657 0.0008860668714540998 0.0004046497297180447
0.00019754404782031527 -0.0007868220444137169 -0.0056108613544142896
0.00012292656024534597 0.00022225578732205814 0.0029485886455847357
0.000059135304030423 0.0001960808270820464 3.0799017983337165e-6
-0.00011621469596881839 0.00008520291582821893 -0.00022515261062644058
-0.00004556469596831336 7.2168714546682475e-6 -2.6613544132268415e-6
I dont understand what do they mean by the scaling factor
on the section where they describe this procedure.
http://cms.mpi.univie.ac.at/vasp/vasp/POSCAR_file.html
"As previously the first line supplies a switch between cartesian coordinates and direct coordinates. On the next lines the initial velocities are provided. They are given in units (/fs, no multiplication with the scaling factor in this case) or (direct lattice vector/timestep)."
3) How one can confirm that the supplied velocities are actually taken in the calculation.
I looked at the OUTCAR and find no evidence.
But, when i don't supply these initial velocities, it says that the initial velocities are not read in.
Please help.
1) During MD, when initial velocities are not provided, it calculates by itself using Maxwell boltzmann distribution. Is there anyway that we can see these velocities.
2) When the velocities are manually supplied in the POSCAR, what is the format. Can anyone provide example.
I used the below format for a system with 13 atoms.
Is this right.
O C W
1.00000000000000
30.0000000000000000 0.0000000000000000 0.0000000000000080
0.0000000000000000 30.0000000000000000 0.0000000000000050
0.0000000000000070 0.0000000000000070 30.0000000000000000
O C W
6 6 1
Direct
0.60803984 0.5 0.5
0.39196016 0.5 0.5
0.5 0.60803984 0.5
0.5 0.39196016 0.5
0.5 0.5 0.60803984
0.5 0.5 0.39196016
0.5 0.56924576 0.5
0.5 0.43075424 0.5
0.5 0.5 0.56924576
0.5 0.5 0.43075424
0.56924576 0.5 0.5
0.43075424 0.5 0.5
0.5 0.5 0.5
-0.0009500646959681771 0.00015729464158412024 -0.00019558904034565843
0.0017851853040324558 -0.00001746089867484154 0.00013806633151759268
0.00002635753390306727 -0.000956833128546547 -0.00014128509974974053
0.0001606130741621412 0.0001002168714552331 -0.00006668760907879347
-0.00045308701003618946 -0.00006460938320967939 0.0045900386455848905
-0.00019334238189980745 -0.00006675687388040273 -0.002098461354414318
0.0003433713484046032 0.0004165668714537551 -0.0004449224385452537
-0.000409750740340657 0.0008860668714540998 0.0004046497297180447
0.00019754404782031527 -0.0007868220444137169 -0.0056108613544142896
0.00012292656024534597 0.00022225578732205814 0.0029485886455847357
0.000059135304030423 0.0001960808270820464 3.0799017983337165e-6
-0.00011621469596881839 0.00008520291582821893 -0.00022515261062644058
-0.00004556469596831336 7.2168714546682475e-6 -2.6613544132268415e-6
I dont understand what do they mean by the scaling factor
on the section where they describe this procedure.
http://cms.mpi.univie.ac.at/vasp/vasp/POSCAR_file.html
"As previously the first line supplies a switch between cartesian coordinates and direct coordinates. On the next lines the initial velocities are provided. They are given in units (/fs, no multiplication with the scaling factor in this case) or (direct lattice vector/timestep)."
3) How one can confirm that the supplied velocities are actually taken in the calculation.
I looked at the OUTCAR and find no evidence.
But, when i don't supply these initial velocities, it says that the initial velocities are not read in.
Please help.