Temperature keeping increasing in long MD run (100 ps +)

[abalone]

I am trying to run an ab initio molecular dynamics for a long time.
I used a 64 atom cell (222) or 128 atom cell (422). And I used gamma point only (vasp 4.6).

To run a long NVE. I started with a sufficient long NVT to reach designation temperature(20000 steps or more). And then switch to NVE and run for another 20000 steps. Then I start to collect data for 100000 steps. I found that the temperature is keep increasing (or decreasing) sometimes during the MD run. The temperature is fluctuating but the average value keep increase/decrease.

For example, for 64 atom MgO, I started from ~550 K, but after 100000 steps (POTIM=1). The average temperature is ~ 680 K. This is not due to normal fluctuation because I averaged the temperature over 1000 steps.

In another case, I start from ~300 K, but temperature drops to 260 K after 100000 steps.

The increase/decrease are nearly linear if the temperature vs time is plotted. It doesn't seem to reach convergence if even longer running time is used.

Can anybody help me with the issue?
Your help is greatly appreciated.

My INCAR file is attached for your reference.

SYSTEM = MgO - MD

Start parameter for this Run:
NWRITE = 0
ISTART = 0 job : 0-new 1-cont from WAVECAR 2-samecut
ICHARG = 2 0-from ini-wf 1-read CHGCAR 2-superposition of ACD
INIWAV = 1 0-lowest 1-random
ISPIN = 1
# MAGMOM = 23*1 23*-1 -1 1
ISYM = 0 0-nonsym 1-usesym
PREC = low
# GGA = 91
# VOSKOWN = 1 0-usual 1-magnetic
Writing Files
LCHARG = F
LWAVE = F

Electronic Relaxation
# ENCUT = 350
EDIFF = 1E-04 stopping-criterion for ELM
LREAL = Auto
NELMIN = 4
Ionic Relaxation and MD
# ISIF = 7
# SMASS = -1
NSW = 100001
NBLOCK = 1
# KBLOCK = 1
IBRION = 0 -1-fixed 0-MD 1-quasi-New 2-CG 3-DMD
TEBEG = 545 start temperature
TEEND = 545 final temperature
# EDIFFG = -0.01 stopping-criterion for IOM
POTIM = 1
# NBANDS = 256

DOS related values:
ISMEAR = 0
SIGMA = 0.05
# EMIN = -7
# EMAX = 3
# RWIGS = 1.029 0.769
# LORBIT = 11
Algorithm:
IALGO = 48
# NPAR = 1

[abalone]

Already find the solution on VASP website.

[gst]

What was the solution? I'm facing the same problem of temperature drop and I can't find a solution to that.
My INCAR file reads:

SYSTEM = MD
NSW = 50000
IBRION = 0
SMASS = -3
POTIM = 3.00
TEBEG = 2000
TEEND = 2000
NBLOCK = 100
ISIF = 0
PREC = Low
ENCUT = 175
ISYM = 0
EDIFF = 1.0E-03
ISMEAR = 0
SIGMA = 0.1
IALGO = 48
LREAL = T
LPLANE = T
NPAR = 2
NSIM = 8
NELMIN = 2
MAXMIX = 50
BMIX = 2.0
LWAVE = F
LCHARG = F
APACO = 10.0

[SKM]

Hi Admin,

i am also getting similar issue as per topic. its not clear how

@adalone

resolved it as mentioned.
I am running a system with 139 atoms, with 3 different molecule clusters in the system. The system is expected to be periodic.
As i want ISIF=3 run, and in fact NpT ensemble should right choice as per my needs, but i am not clear about selecting the LANGEVIN_GAMMA-tag in such system and how to assign a value to it. So i selected NpH ensemble wherein only LANGEVIN_GAMMA_L tag is needed. My INCAR is as below

SYSTEM = MOF-1-C2H2
LPLANE=.TRUE.
LSCALU = .FALSE.
NPAR = 16
NSIM = 16

Startparameter for this Run:
ISTART = 0
LWAVE = .FALSE. do not write WAVECAR file
LCHARG = .FALSE. do not write CHGCAR file
IVDW = 11
ENCUT = 450
Electronic Relaxation 1
PREC = Medium Medium=default, Low, High; affects ENMAX, mesh, pspot
NELM = 300 max number of electronic steps
NELMIN = 2
EDIFF = 1E-04 energy stopping-criterion for electr. iterations
EDIFFG = -.02 force stopping-criterion for geometry steps

Ionic Relaxation
NSW = 4000 max number of geometry steps
IBRION = 0 ionic relax: 0-MD 1-quasi-New 2-CG
ISIF = 3 (0:force=y stress=n ions=y shape=n volume=n,

# 2:f=y s=y i=y s=n v=n, 4:f=y s=y i=y s=y v=n, 5:f=y s=y i=n s=y v=n)
ISYM = 0 1=use symmetry, 0 = no symmetry
POTIM = 2
LANGEVIN_GAMMA_L = 0.0

#AIMD caculation
SMASS = 2.5
NWRITE = 2
TEBEG = 300
TEEND = 300
MDALGO = 3
NBLOCK=1
KBLOCK=50
MAXMIX=40
AMIN = 0.01
#ANDERSEN_PROB = 0.1

DOS related values:
ISMEAR = -1 -4-tet -1-fermi 1=Methfessel/Paxton 1.order
SIGMA = .2 broadening in eV

Electronic Relaxation
LREAL = Auto real-space projectioni
ADDGRID = .TRUE.

Now the run stopped after about 1 hr and the temperatures are abnormally increasing. The 'grep T= OSZICAR' gives the following output, shown only relevant portion to reduce content

1 T= 303. E= -.94408164E+03 F= -.94963422E+03 E0= -.94933867E+03 EK= 0.55526E+01 SP= 0.000
2 T= 241. E= -.94369846E+03 F= -.94811536E+03 E0= -.94781958E+03 EK= 0.44169E+01 SP= 0.000
3 T= 199. E= -.94382671E+03 F= -.94748802E+03 E0= -.94719142E+03 EK= 0.36613E+01 SP= 0.000
4 T= 157. E= -.94388013E+03 F= -.94675631E+03 E0= -.94645860E+03 EK= 0.28762E+01 SP= 0.000
5 T= 119. E= -.94357107E+03 F= -.94576175E+03 E0= -.94546312E+03 EK= 0.21907E+01 SP= 0.000
6 T= 166. E= -.94399817E+03 F= -.94705276E+03 E0= -.94675382E+03 EK= 0.30546E+01 SP= 0.000
7 T= 143. E= -.94365472E+03 F= -.94628746E+03 E0= -.94598809E+03 EK= 0.26327E+01 SP= 0.000
8 T= 165. E= -.94384702E+03 F= -.94686858E+03 E0= -.94656877E+03 EK= 0.30216E+01 SP= 0.000
9 T= 161. E= -.94387648E+03 F= -.94682655E+03 E0= -.94652650E+03 EK= 0.29501E+01 SP= 0.000
10 T= 145. E= -.94361808E+03 F= -.94627455E+03 E0= -.94597502E+03 EK= 0.26565E+01 SP= 0.000
11 T= 184. E= -.94396780E+03 F= -.94733755E+03 E0= -.94703892E+03 EK= 0.33698E+01 SP= 0.000
12 T= 156. E= -.94365101E+03 F= -.94652264E+03 E0= -.94622457E+03 EK= 0.28716E+01 SP= 0.000
13 T= 173. E= -.94384547E+03 F= -.94702556E+03 E0= -.94672727E+03 EK= 0.31801E+01 SP= 0.000
14 T= 157. E= -.94384164E+03 F= -.94673151E+03 E0= -.94643246E+03 EK= 0.28899E+01 SP= 0.000
15 T= 138. E= -.94364725E+03 F= -.94617494E+03 E0= -.94587560E+03 EK= 0.25277E+01 SP= 0.000
16 T= 165. E= -.94392195E+03 F= -.94694531E+03 E0= -.94664633E+03 EK= 0.30234E+01 SP= 0.000
17 T= 142. E= -.94364664E+03 F= -.94626107E+03 E0= -.94596220E+03 EK= 0.26144E+01 SP= 0.000
18 T= 169. E= -.94383583E+03 F= -.94694691E+03 E0= -.94664759E+03 EK= 0.31111E+01 SP= 0.000
19 T= 163. E= -.94380371E+03 F= -.94680392E+03 E0= -.94650382E+03 EK= 0.30002E+01 SP= 0.000
.....
.....
37 T= 155. E= -.94374310E+03 F= -.94658222E+03 E0= -.94628309E+03 EK= 0.28391E+01 SP= 0.000
38 T= 154. E= -.94378213E+03 F= -.94661636E+03 E0= -.94631711E+03 EK= 0.28342E+01 SP= 0.000
39 T= 148. E= -.94378641E+03 F= -.94649834E+03 E0= -.94619866E+03 EK= 0.27119E+01 SP= 0.000
40 T= 139. E= -.94369486E+03 F= -.94624347E+03 E0= -.94594381E+03 EK= 0.25486E+01 SP= 0.000
41 T= 144. E= -.94376536E+03 F= -.94640209E+03 E0= -.94610292E+03 EK= 0.26367E+01 SP= 0.000
42 T= 145. E= -.94373754E+03 F= -.94639943E+03 E0= -.94610113E+03 EK= 0.26619E+01 SP= 0.000
43 T= 148. E= -.94373661E+03 F= -.94645086E+03 E0= -.94615325E+03 EK= 0.27143E+01 SP= 0.000
44 T= 157. E= -.94381118E+03 F= -.94669231E+03 E0= -.94639502E+03 EK= 0.28811E+01 SP= 0.000
45 T= 153. E= -.94367873E+03 F= -.94647967E+03 E0= -.94618253E+03 EK= 0.28009E+01 SP= 0.000
46 T= 160. E= -.94376603E+03 F= -.94671084E+03 E0= -.94641406E+03 EK= 0.29448E+01 SP= 0.000
47 T= 158. E= -.94373315E+03 F= -.94662662E+03 E0= -.94633042E+03 EK= 0.28935E+01 SP= 0.000
48 T= 150. E= -.94369959E+03 F= -.94644733E+03 E0= -.94615125E+03 EK= 0.27477E+01 SP= 0.000
49 T= 157. E= -.94382003E+03 F= -.94669564E+03 E0= -.94639903E+03 EK= 0.28756E+01 SP= 0.000
50 T= 150. E= -.94365001E+03 F= -.94639656E+03 E0= -.94609946E+03 EK= 0.27465E+01 SP= 0.000
51 T= 167. E= -.94376128E+03 F= -.94681822E+03 E0= -.94652144E+03 EK= 0.30569E+01 SP= 0.000
52 T= 171. E= -.94372324E+03 F= -.94686850E+03 E0= -.94657269E+03 EK= 0.31453E+01 SP= 0.000
53 T= 168. E= -.94367708E+03 F= -.94676893E+03 E0= -.94647403E+03 EK= 0.30918E+01 SP= 0.000
54 T= 175. E= -.94384246E+03 F= -.94706088E+03 E0= -.94676647E+03 EK= 0.32184E+01 SP= 0.000
....
....
67 T= 153. E= -.94359757E+03 F= -.94641441E+03 E0= -.94611902E+03 EK= 0.28168E+01 SP= 0.000
68 T= 157. E= -.94356338E+03 F= -.94644300E+03 E0= -.94614780E+03 EK= 0.28796E+01 SP= 0.000
69 T= 165. E= -.94374785E+03 F= -.94677778E+03 E0= -.94648244E+03 EK= 0.30299E+01 SP= 0.000
70 T= 143. E= -.94346491E+03 F= -.94608396E+03 E0= -.94578846E+03 EK= 0.26190E+01 SP= 0.000
71 T= 166. E= -.94362289E+03 F= -.94667356E+03 E0= -.94637851E+03 EK= 0.30507E+01 SP= 0.000
72 T= 154. E= -.94350418E+03 F= -.94632494E+03 E0= -.94603054E+03 EK= 0.28208E+01 SP= 0.000
73 T= 168. E= -.94350129E+03 F= -.94658549E+03 E0= -.94629087E+03 EK= 0.30842E+01 SP= 0.000
74 T= 181. E= -.94368159E+03 F= -.94700593E+03 E0= -.94671016E+03 EK= 0.33243E+01 SP= 0.000
75 T= 159. E= -.94334020E+03 F= -.94626278E+03 E0= -.94596571E+03 EK= 0.29226E+01 SP= 0.000
76 T= 183. E= -.94348481E+03 F= -.94684287E+03 E0= -.94654547E+03 EK= 0.33581E+01 SP= 0.000
77 T= 155. E= -.94335163E+03 F= -.94619349E+03 E0= -.94589615E+03 EK= 0.28419E+01 SP= 0.000
78 T= 161. E= -.94336629E+03 F= -.94632409E+03 E0= -.94602665E+03 EK= 0.29578E+01 SP= 0.000
79 T= 170. E= -.94355405E+03 F= -.94667248E+03 E0= -.94637392E+03 EK= 0.31184E+01 SP= 0.000
80 T= 141. E= -.94299749E+03 F= -.94559408E+03 E0= -.94529447E+03 EK= 0.25966E+01 SP= 0.000
81 T= 187. E= -.94310406E+03 F= -.94654276E+03 E0= -.94624344E+03 EK= 0.34387E+01 SP= 0.000
82 T= 158. E= -.94295216E+03 F= -.94585642E+03 E0= -.94555824E+03 EK= 0.29043E+01 SP= 0.000
83 T= 173. E= -.94299354E+03 F= -.94616877E+03 E0= -.94587169E+03 EK= 0.31752E+01 SP= 0.000
84 T= 202. E= -.94315892E+03 F= -.94686171E+03 E0= -.94656491E+03 EK= 0.37028E+01 SP= 0.000
85 T= 140. E= -.94249529E+03 F= -.94506530E+03 E0= -.94476833E+03 EK= 0.25700E+01 SP= 0.000
86 T= 190. E= -.94271141E+03 F= -.94619137E+03 E0= -.94589489E+03 EK= 0.34800E+01 SP= 0.000
87 T= 142. E= -.94253568E+03 F= -.94513711E+03 E0= -.94484103E+03 EK= 0.26014E+01 SP= 0.000
........
.......
......
97 T= 224. E= -.94234556E+03 F= -.94646180E+03 E0= -.94616517E+03 EK= 0.41162E+01 SP= 0.000
98 T= 183. E= -.94236610E+03 F= -.94572167E+03 E0= -.94542590E+03 EK= 0.33556E+01 SP= 0.000
99 T= 178. E= -.94233243E+03 F= -.94559745E+03 E0= -.94530192E+03 EK= 0.32650E+01 SP= 0.000
100 T= 212. E= -.94235116E+03 F= -.94624808E+03 E0= -.94595247E+03 EK= 0.38969E+01 SP= 0.000
101 T= 193. E= -.94291388E+03 F= -.94646532E+03 E0= -.94616984E+03 EK= 0.35514E+01 SP= 0.000
102 T= 180. E= -.94171293E+03 F= -.94501479E+03 E0= -.94471963E+03 EK= 0.33019E+01 SP= 0.000
103 T= 299. E= -.94021381E+03 F= -.94570164E+03 E0= -.94540691E+03 EK= 0.54878E+01 SP= 0.000
104 T= 210. E= -.94012312E+03 F= -.94398462E+03 E0= -.94368817E+03 EK= 0.38615E+01 SP= 0.000
105 T= 165. E= -.94014918E+03 F= -.94317560E+03 E0= -.94287137E+03 EK= 0.30264E+01 SP= 0.000
106 T= 155. E= -.94017448E+03 F= -.94302451E+03 E0= -.94271774E+03 EK= 0.28500E+01 SP= 0.000
107 T= 177. E= -.94007631E+03 F= -.94333273E+03 E0= -.94303298E+03 EK= 0.32564E+01 SP= 0.000
108 T= 264. E= -.94014531E+03 F= -.94499950E+03 E0= -.94470486E+03 EK= 0.48542E+01 SP= 0.000
109 T= 303. E= -.94109789E+03 F= -.94665495E+03 E0= -.94636034E+03 EK= 0.55571E+01 SP= 0.000
110 T= 1327. E= -.91075282E+03 F= -.93510467E+03 E0= -.93480973E+03 EK= 0.24352E+02 SP= 0.000
111 T= 6377. E= -.82368542E+03 F= -.94073064E+03 E0= -.94017847E+03 EK= 0.11705E+03 SP= 0.000
112 T= 6326. E= -.82245036E+03 F= -.93857045E+03 E0= -.93800436E+03 EK= 0.11612E+03 SP= 0.000
113 T= 6307. E= -.82212047E+03 F= -.93788707E+03 E0= -.93732412E+03 EK= 0.11577E+03 SP= 0.000
114 T= 5379. E= -.83338532E+03 F= -.93211915E+03 E0= -.93146880E+03 EK= 0.98734E+02 SP= 0.000
115 T= 4695. E= -.84960938E+03 F= -.93579501E+03 E0= -.93522231E+03 EK= 0.86186E+02 SP= 0.000
116 T= 4619. E= -.84883052E+03 F= -.93361303E+03 E0= -.93299702E+03 EK= 0.84783E+02 SP= 0.000
117 T= 4600. E= -.84997493E+03 F= -.93440209E+03 E0= -.93378443E+03 EK= 0.84427E+02 SP= 0.000
118 T= 4592. E= -.85061400E+03 F= -.93489606E+03 E0= -.93435910E+03 EK= 0.84282E+02 SP= 0.000
119 T= 4525. E= -.85088327E+03 F= -.93393112E+03 E0= -.93334074E+03 EK= 0.83048E+02 SP= 0.000
120 T= 4543. E= -.85117432E+03 F= -.93456345E+03 E0= -.93397825E+03 EK= 0.83389E+02 SP= 0.000
121 T= 4592. E= -.84916334E+03 F= -.93345137E+03 E0= -.93281009E+03 EK= 0.84288E+02 SP= 0.000
122 T= 9464. E= -.75070102E+03 F= -.92441843E+03 E0= -.92388728E+03 EK= 0.17372E+03 SP= 0.000
123 T= 17637. E= -.61084331E+03 F= -.93456550E+03 E0= -.93400164E+03 EK= 0.32372E+03 SP= 0.000
124 T= 17562. E= -.60924624E+03 F= -.93159619E+03 E0= -.93103540E+03 EK= 0.32235E+03 SP= 0.000
125 T= 17793. E= -.60626135E+03 F= -.93285373E+03 E0= -.93224065E+03 EK= 0.32659E+03 SP= 0.000
126 T= 17860. E= -.60612314E+03 F= -.93393654E+03 E0= -.93330166E+03 EK= 0.32781E+03 SP= 0.000
127 T= 17875. E= -.60581803E+03 F= -.93390749E+03 E0= -.93326531E+03 EK= 0.32809E+03 SP= 0.000
128 T= 18455. E= -.59551149E+03 F= -.93425859E+03 E0= -.93376967E+03 EK= 0.33875E+03 SP= 0.000
129 T= 18413. E= -.59663367E+03 F= -.93460689E+03 E0= -.93422572E+03 EK= 0.33797E+03 SP= 0.000
130 T= 17714. E= -.60732642E+03 F= -.93247529E+03 E0= -.93190038E+03 EK= 0.32515E+03 SP= 0.000
131 T= 17694. E= -.60713348E+03 F= -.93190933E+03 E0= -.93143260E+03 EK= 0.32478E+03 SP= 0.000
132 T= 17771. E= -.60452657E+03 F= -.93072141E+03 E0= -.93005113E+03 EK= 0.32619E+03 SP= 0.000
133 T= 17774. E= -.60458771E+03 F= -.93083798E+03 E0= -.93014833E+03 EK= 0.32625E+03 SP= 0.000
134 T= 17760. E= -.60464334E+03 F= -.93062201E+03 E0= -.92995358E+03 EK= 0.32598E+03 SP= 0.000
135 T= 17287. E= -.61197701E+03 F= -.92928457E+03 E0= -.92879347E+03 EK= 0.31731E+03 SP= 0.000
136 T= 16718. E= -.62348044E+03 F= -.93033472E+03 E0= -.92983091E+03 EK= 0.30685E+03 SP= 0.000
137 T= 18375. E= -.59019592E+03 F= -.92747828E+03 E0= -.92701744E+03 EK= 0.33728E+03 SP= 0.000
138 T= 20445. E= -.55337775E+03 F= -.92864356E+03 E0= -.92802710E+03 EK= 0.37527E+03 SP= 0.000
139 T= 20567. E= -.55225658E+03 F= -.92976803E+03 E0= -.92906216E+03 EK= 0.37751E+03 SP= 0.000
140 T= 20266. E= -.55495128E+03 F= -.92692738E+03 E0= -.92643947E+03 EK= 0.37198E+03 SP= 0.000
141 T= 20037. E= -.56228594E+03 F= -.93007241E+03 E0= -.92934729E+03 EK= 0.36779E+03 SP= 0.000
142 T= 20031. E= -.56245269E+03 F= -.93011404E+03 E0= -.92948094E+03 EK= 0.36766E+03 SP= 0.000
143 T= 19977. E= -.56324453E+03 F= -.92992219E+03 E0= -.92929767E+03 EK= 0.36668E+03 SP= 0.000
144 T= 18225. E= -.59289161E+03 F= -.92740837E+03 E0= -.92684839E+03 EK= 0.33452E+03 SP= 0.000
145 T= 16650. E= -.62314335E+03 F= -.92875482E+03 E0= -.92806569E+03 EK= 0.30561E+03 SP= 0.000
146 T= 16645. E= -.62255473E+03 F= -.92807353E+03 E0= -.92734093E+03 EK= 0.30552E+03 SP= 0.000
147 T= 16613. E= -.62269259E+03 F= -.92762461E+03 E0= -.92704697E+03 EK= 0.30493E+03 SP= 0.000
148 T= 16656. E= -.62103949E+03 F= -.92676286E+03 E0= -.92631807E+03 EK= 0.30572E+03 SP= 0.000
149 T= 16817. E= -.61879073E+03 F= -.92746475E+03 E0= -.92687553E+03 EK= 0.30867E+03 SP= 0.000
150 T= 16863. E= -.61832571E+03 F= -.92785306E+03 E0= -.92731819E+03 EK= 0.30953E+03 SP= 0.000
151 T= 16843. E= -.61886573E+03 F= -.92802500E+03 E0= -.92742604E+03 EK= 0.30916E+03 SP= 0.000
152 T= 15098. E= -.64893748E+03 F= -.92605529E+03 E0= -.92549557E+03 EK= 0.27712E+03 SP= 0.000
153 T= 13767. E= -.67357275E+03 F= -.92625929E+03 E0= -.92556987E+03 EK= 0.25269E+03 SP= 0.000
154 T= 13636. E= -.67528726E+03 F= -.92557388E+03 E0= -.92483612E+03 EK= 0.25029E+03 SP= 0.000
155 T= 13540. E= -.67706657E+03 F= -.92559891E+03 E0= -.92458103E+03 EK= 0.24853E+03 SP= 0.000
156 T= 14439. E= -.65777869E+03 F= -.92280380E+03 E0= -.92200347E+03 EK= 0.26503E+03 SP= 0.000
157 T= 15379. E= -.64091591E+03 F= -.92319934E+03 E0= -.92205073E+03 EK= 0.28228E+03 SP= 0.000
158 T= 15267. E= -.64031031E+03 F= -.92053712E+03 E0= -.91958295E+03 EK= 0.28023E+03 SP= 0.000
159 T= 15267. E= -.64412134E+03 F= -.92434854E+03 E0= -.92349227E+03 EK= 0.28023E+03 SP= 0.000
160 T= 15276. E= -.64438220E+03 F= -.92476943E+03 E0= -.92381732E+03 EK= 0.28039E+03 SP= 0.000
161 T= 15141. E= -.64421426E+03 F= -.92212835E+03 E0= -.92118165E+03 EK= 0.27791E+03 SP= 0.000
162 T= 31490. E= -.31993600E+03 F= -.89794461E+03 E0= -.89725124E+03 EK= 0.57801E+03 SP= 0.000
163 T= 62927. E= 0.23614297E+03 F= -.91889117E+03 E0= -.91804048E+03 EK= 0.11550E+04 SP= 0.000
164 T= 62636. E= 0.23697677E+03 F= -.91271710E+03 E0= -.91187775E+03 EK= 0.11497E+04 SP= 0.000
165 T= 62342. E= 0.23495951E+03 F= -.90933188E+03 E0= -.90838918E+03 EK= 0.11443E+04 SP= 0.000
166 T= 62252. E= 0.23631884E+03 F= -.90631490E+03 E0= -.90534747E+03 EK= 0.11426E+04 SP= 0.000
167 T= 62493. E= 0.24345953E+03 F= -.90360647E+03 E0= -.90235392E+03 EK= 0.11471E+04 SP= 0.000
168 T= 62579. E= 0.24454123E+03 F= -.90409401E+03 E0= -.90288348E+03 EK= 0.11486E+04 SP= 0.000
169 T= 62029. E= 0.23714047E+03 F= -.90140601E+03 E0= -.90031055E+03 EK= 0.11385E+04 SP= 0.000
170 T= 61617. E= 0.22775614E+03 F= -.90322717E+03 E0= -.90202733E+03 EK= 0.11310E+04 SP= 0.000
171 T= 61623. E= 0.22967893E+03 F= -.90141605E+03 E0= -.90022465E+03 EK= 0.11311E+04 SP= 0.000
172 T= 61369. E= 0.22569241E+03 F= -.90073587E+03 E0= -.89964556E+03 EK= 0.11264E+04 SP= 0.000
173 T= 94934. E= 0.88359149E+03 F= -.85892899E+03 E0= -.85799865E+03 EK= 0.17425E+04 SP= 0.000
174 T= ****** E= 0.18067732E+04 F= -.88841601E+03 E0= -.88742298E+03 EK= 0.26952E+04 SP= 0.000
175 T= ****** E= 0.18097354E+04 F= -.88263335E+03 E0= -.88161723E+03 EK= 0.26924E+04 SP= 0.000
176 T= ****** E= 0.18212885E+04 F= -.87969702E+03 E0= -.87869684E+03 EK= 0.27010E+04 SP= 0.000
........
.......

191 T= ****** E= 0.54238027E+06 F= -.81722292E+03 E0= -.81545875E+03 EK= 0.54320E+06 SP= 0.000
192 T= ****** E= 0.58094556E+06 F= -.69733247E+03 E0= -.69462552E+03 EK= 0.58164E+06 SP= 0.000
193 T= ****** E= 0.58883054E+06 F= -.46063587E+03 E0= -.45699646E+03 EK= 0.58929E+06 SP= 0.000
194 T= ****** E= 0.58849605E+06 F= -.15627450E+03 E0= -.15188863E+03 EK= 0.58865E+06 SP= 0.000
195 T= ****** E= 0.58781291E+06 F= 0.16137453E+03 E0= 0.16615997E+03 EK= 0.58765E+06 SP= 0.000

no error written in log file. but in OUTCAR just before the run stopped, the message is at the end of OUTCAR as

Error EDDDAV: Call to ZHEGV failed. Return code = 38 2 64

This error code, as per my understanding, may be mostly due to atoms overlap or very close to each other. But the primary issue is the abnormality of temperature raise.

Another observation of testing was, when the POTIM was tested with 3 or more, the abnormal temperature starting much earlier steps, and seems logical with respect to this time tag, as the system may be reaching that abnormality much quicker than when POTIM has less value.

What could went wrong here please?
Regards

[SKM]

hi
i have changed the MDALGO=1
and uncommented ANDERSON_PROBE in my INCAR
then it is not increasing the temperature.
Regards

[martin.schlipf]

Generally for MD simulations you need to take care that your time step matches with the dynamics of your system, i.e., is compatible with the temperature and the bonds in your systems. The faster your dynamics are, the smaller your time step has to be and vice versa you can choose a much larger time step for MD simulations with very slow dynamics to be more efficient.

One possible method to find an appropriate time step is to monitor an NVE ensemble for some time and by trial and error determine a time step where the energy drift is small enough. You can use then a thermostat to remove the remaining drift in the system. However if your drift is very large, you may alter the dynamics of the system. Here is an article that elaborates a bit more on the complications of choosing the right time step.

[SKM]

Thank you Martin, for the input. will read through the article.
Regards