unknown identifier in data file

I got an error during the first line of coordinate

500 atoms
1 atom types

0.0 20.0 xlo xhi
0.0 20.0 ylo yhi
0.0 20.0 zlo zhi

Masses

1 12.01

Atoms

1 1 13.2435 4.24989 7.91613
2 1 0.0892596 0.186008 6.2443
3 1 6.19411 4.41293 8.14057
4 1 18.5436 2.54084 3.83973
5 1 2.44589 8.08014 2.87701
6 1 13.9768 8.48819 1.03893
7 1 1.33403 1.11758 3.18401
8 1 13.6601 5.06257 6.64556
9 1 11.8491 7.58044 4.51208
10 1 14.5108 2.39681 3.16877
11 1 13.7541 5.89791 6.11987
12 1 17.0849 6.33191 0.413567
13 1 3.49075 9.11789 4.38513
14 1 6.41312 5.31233 4.33686
15 1 19.9885 6.81406 3.86823
16 1 13.339 9.3166 4.16706
17 1 16.6602 8.01587 2.71518
18 1 15.5535 6.89293 9.48253
19 1 8.53115 3.11901 1.25108
20 1 11.3501 1.16183 6.9566
21 1 5.92899 8.54582 9.63931
22 1 14.3169 3.57601 1.97912
23 1 3.11449 5.16469 2.86362
24 1 8.81328 4.7386 1.70413
25 1 6.63784 2.19933 4.15113
26 1 8.08987 6.50135 8.20598
27 1 7.36609 1.81987 6.49307
28 1 9.00461 0.430787 0.235404
29 1 7.59025 9.38457 6.38637
30 1 17.099 3.05485 2.84549
31 1 7.99237 7.73617 1.80837
32 1 8.9204 5.12645 0.226193
33 1 19.6158 3.48579 5.62274
34 1 12.8641 6.656 7.44072
35 1 16.2414 9.96031 3.00558
36 1 14.8587 9.5773 5.74346
37 1 10.484 4.23319 7.23091
38 1 8.72891 6.71523 2.83656
39 1 14.0419 2.19105 4.99625
40 1 12.0169 7.41534 9.61134
41 1 3.82478 3.07289 6.13467
42 1 1.18536 2.29578 5.12572
43 1 1.35925 4.86617 5.7239
44 1 1.66287 7.79558 0.243023
45 1 4.85919 8.33822 0.458883
46 1 16.6792 7.06767 6.8645
47 1 17.0918 1.54874 9.74625
48 1 5.24477 8.80128 3.09862
49 1 11.6512 0.933353 6.86603
50 1 17.3346 1.84592 4.43916
51 1 6.46878 0.779621 3.09368
52 1 12.1775 6.57153 7.78633
53 1 13.115 3.86189 6.86145
54 1 0.339672 8.87071 9.95205
55 1 4.02461 1.55531 0.0415514
56 1 6.02265 2.64344 8.23181
57 1 14.9275 6.80101 4.58917
58 1 0.0822527 2.42091 8.20779
59 1 6.12151 4.16551 9.68676
60 1 5.40622 2.26001 3.95068
61 1 19.129 1.91144 5.519
62 1 19.8137 8.72194 9.63634
63 1 18.0333 6.00031 7.19654
64 1 12.1975 3.31062 1.59729
65 1 13.9216 1.02117 2.83991
66 1 10.3852 3.77394 8.60759
67 1 9.5723 1.66962 1.38186
68 1 17.1179 0.838938 0.0258331
69 1 12.6461 2.61116 5.76346
70 6.49538 7.93516 6.21959
71 1 12.8745 2.47539 3.85136
72 1 12.9795 6.88056 1.6079
73 1 4.04358 0.401277 4.26899
74 1 18.4143 9.14432 8.56587
75 1 4.01909 8.8385 8.696
76 1 1.7498 8.96572 6.93662
77 1 4.89932 2.84086 6.37727
78 1 19.2625 4.27016 8.64384
79 1 17.0777 4.52214 3.64815
80 1 11.8527 7.8042 5.16108
81 1 6.01113 9.03831 6.93611
82 1 15.1692 8.08747 6.10242
83 1 17.9951 4.3404 9.08307
84 1 13.2495 4.02483 5.30054
85 1 11.0769 8.65148 5.4893
86 1 18.6734 3.30839 4.03323
87 1 3.53815 5.67073 7.90979
88 1 15.3583 6.68579 8.13301
89 1 14.9369 4.54148 8.7092
90 1 16.4218 1.7707 0.158393
91 1 14.4456 7.03429 5.30809
92 1 10.5116 7.96936 1.05327
93 1 5.8358 2.26613 6.77415
94 1 13.1127 5.08286 7.64422
95 1 3.35137 6.54877 5.11335
96 1 17.9009 0.000259206 4.35647
97 1 19.1944 0.146547 3.00943
98 1 19.555 1.44148 6.91517
99 1 3.256 3.55134 7.4536
100 1 12.5964 7.92935 8.55026
101 1 8.59315 5.11837 4.48784
102 1 7.06309 9.39282 5.16261
103 1 11.7253 6.79132 1.68549
104 1 13.1495 3.37605 1.2759
105 1 4.04484 1.65316 4.60967
106 1 14.7608 4.14359 1.25808
107 1 17.6241 8.75864 6.49637
108 1 4.46523 7.18193 6.6785
109 1 12.5972 1.75886 1.08342
110 1 10.9841 9.12767 8.67362
111 1 17.4646 7.17562 0.640119
112 1 4.33312 6.68804 5.9339
113 1 16.1564 1.03105 8.861
114 1 14.4822 1.94696 2.50756
115 1 13.1866 7.08556 6.94924
116 1 15.8923 2.55758 5.20162
117 1 13.8827 6.36417 2.55243
118 1 18.6363 0.99886 7.83943
119 1 16.6481 4.78416 7.30931
120 1 2.317 1.85085 7.27878
121 1 2.27821 9.91069 9.01907
122 1 9.17758 7.66995 8.82963
123 1 15.4617 4.81487 3.5504
124 1 11.5418 3.11934 6.74879
125 1 5.90639 8.73729 7.59567
126 1 0.361099 8.98935 3.96677
127 1 3.38558 1.50422 1.39696
128 1 9.29018 0.0404863 0.452718
129 1 3.74886 7.01266 1.72926
130 1 16.2767 2.70401 6.26636
131 1 17.3666 1.26074 9.21153
132 1 6.0479 7.11503 2.23257
133 1 2.75417 9.31894 3.45825
134 1 2.87394 2.36959 5.68242
135 1 12.5595 8.19939 7.21143
136 1 16.2684 3.28475 6.84686
137 1 15.2546 3.57367 2.60591
138 1 11.9062 6.94727 2.8433
139 1 7.90394 1.48063 4.9347
140 1 15.7994 0.420065 0.0262082
141 1 7.21283 6.02619 2.18066
142 1 13.9578 9.41197 6.96976
143 1 15.4306 1.55979 15.3722
144 1 17.4385 9.38527 18.2623
145 1 16.5744 6.36844 14.4033
146 1 7.56246 2.33346 18.4185
147 1 15.4951 6.44483 18.3344
148 1 18.3168 9.96919 12.2189
149 1 2.74065 2.10254 17.3468
150 1 6.30132 6.36605 14.2203
151 1 12.9269 2.24304 18.693
152 1 12.9962 7.55858 17.0886
153 1 8.3861 5.12046 19.6364
154 1 1.24962 2.28465 18.0476
155 1 17.8383 7.61703 19.4132
156 1 19.1601 4.08241 13.0828
157 1 1.6687 5.86264 13.4513
158 1 10.8721 7.63609 19.8376
159 1 18.1378 2.23115 18.9949
160 1 14.1863 8.37977 18.7194
161 1 13.7493 4.98953 18.9891
162 1 14.5334 2.85305 11.2798
163 1 10.2865 4.49397 10.0982
164 1 17.8181 9.48767 19.2295
165 1 14.9717 9.79096 16.6456
166 1 1.88783 8.69249 14.7584
167 1 10.3094 9.76562 10.7795
168 1 5.86356 8.85344 19.8127
169 1 12.5118 5.93879 13.1779
170 1 0.674067 9.03906 19.5516
171 1 3.56062 3.41842 13.4231
172 1 1.46269 3.41725 13.6588
173 1 15.6784 7.4834 13.4361
174 1 1.54342 0.210396 16.1178
175 1 12.4402 2.03814 15.0714
176 1 5.26103 2.11578 19.936
177 1 3.97268 8.87569 13.7131
178 1 18.4536 9.71962 17.7287
179 1 7.04485 2.74863 16.2391
180 1 8.98445 1.7049 14.2415
181 1 8.7357 0.979123 16.1282
182 1 5.9612 9.90612 12.0751
183 1 10.2613 1.77846 10.5463
184 1 18.3548 8.3738 18.5048
185 1 8.79895 3.99448 15.1567
186 1 17.807 1.75279 19.1672
187 1 12.0512 4.07193 16.9486
188 1 3.04433 6.13765 15.5247
189 1 13.3685 4.00027 12.6036
190 1 8.10544 8.11778 15.5114
191 1 8.37284 2.29747 13.5777
192 1 0.524004 6.94305 11.7882
193 1 10.4257 5.42628 19.557
194 1 10.421 5.12852 15.0044
195 1 7.7006 4.00023 11.8272
196 1 8.10261 0.505435 14.8542
197 1 14.6563 7.65134 16.0976
198 1 9.80456 5.17397 18.994
199 1 6.55136 8.74379 16.8861
200 1 13.6722 8.68294 14.218
201 1 1.47439 0.0914014 16.1828
202 1 15.4963 6.90375 11.2664
203 1 14.2859 2.62219 11.1722
204 1 12.0917 5.2082 14.2962
205 1 18.1568 1.31724 18.8017
206 1 13.7507 8.49618 15.3665
207 1 2.82872 2.29875 15.0342
208 1 10.8947 6.49826 16.3319
209 1 9.59391 4.86888 11.3008
210 1 2.35295 5.98896 16.4053
211 1 13.709 6.41702 10.7901
212 1 18.0996 0.817148 13.7987
213 1 19.1554 4.18489 15.3727
214 1 8.39898 1.68941 13.8485
215 1 4.58619 0.0758655 15.0722
216 1 6.13469 5.72564 10.8079
217 1 6.98291 1.84152 10.4161
218 1 19.8695 6.97683 19.5225
219 1 0.905758 3.08165 13.2394
220 1 15.4904 7.92037 17.6139
221 1 2.10397 1.45534 19.8965
222 1 9.89745 6.43853 12.4446
223 1 12.8972 3.62818 18.8255
224 1 17.6345 2.81991 14.2583
225 1 13.0911 1.74054 13.2146
226 1 11.648 8.27864 19.0427
227 1 12.6202 8.29963 11.9324
228 1 7.99199 1.29945 19.8699
229 1 5.55861 3.4921 11.6852
230 1 13.5972 8.88527 14.8133
231 1 4.88496 1.524 13.8945
232 1 3.55329 0.111627 16.1095
233 1 6.74658 9.69788 12.2021
234 1 15.8483 2.77096 11.5619
235 1 3.64293 6.73874 17.9535
236 1 7.52937 6.20199 16.8229
237 1 14.3799 2.24663 19.1199
238 1 4.671 5.51144 10.7482
239 1 15.0916 4.9289 19.9978
240 1 8.8372 6.8908 13.6099
241 1 11.2244 9.28653 18.6663
242 1 3.58946 8.02267 16.973
243 1 1.4832 8.09994 15.694
244 1 8.94064 5.26296 14.591
245 1 5.50608 0.668567 16.5988
246 1 16.7515 1.97016 12.4232
247 1 18.1487 5.49842 12.0262
248 1 4.71362 1.84634 11.4057
249 1 15.0724 2.32471 11.3245
250 1 11.1079 9.68231 10.6281
251 1 1.93018 0.519875 17.5422
252 1 16.078 3.76967 16.9237
253 1 9.04632 1.53808 10.4493
254 1 1.33335 9.5693 11.2853
255 1 15.9473 5.82919 11.2539
256 1 4.80277 0.0926593 17.3246
257 1 12.4379 3.20448 17.7204
258 1 3.38819 5.22717 13.035
259 1 11.0597 0.434322 19.6573
260 1 19.724 0.917117 13.986
261 1 10.8214 15.8462 6.28099
262 1 4.51697 16.7567 9.3356
263 1 9.77545 15.9731 0.670409
264 1 19.1132 14.8072 3.91653
265 1 5.1342 10.5759 9.79915
266 1 9.68734 15.1441 6.83753
267 1 3.297 12.6234 1.48764
268 1 8.26313 18.3556 2.00311
269 1 1.10426 19.2505 2.38928
270 1 14.0698 11.0217 2.02643
271 1 18.1255 15.7451 7.54594
272 1 4.17287 13.398 0.592639
273 1 0.475838 17.413 0.195478
274 1 6.93239 12.6346 9.59114
275 1 18.2328 18.6673 0.63456
276 1 14.6481 10.1758 5.40319
277 1 19.4953 17.261 5.83979
278 1 2.90108 18.3833 8.53846
279 1 7.94771 17.1825 6.37201
280 1 17.0343 15.5663 2.52271
281 1 1.78799 10.8102 6.71114
282 1 14.1084 19.1708 3.38156
283 1 17.91 13.3746 6.17525
284 1 16.4367 12.3962 3.68641
285 1 17.5698 15.533 2.34892
286 1 18.297 17.1373 7.33331
287 1 16.6347 19.7112 6.76731
288 1 18.1042 17.2861 7.43456
289 1 12.728 19.6053 5.66896
290 1 15.6837 15.2699 1.23668
291 1 4.91303 13.3199 7.96181
292 1 15.2968 12.9689 8.70669
293 1 13.3691 14.1753 4.88193
294 1 10.5848 19.1543 6.19676
295 1 1.63007 16.5315 4.62865
296 1 9.202 17.9966 9.32436
297 1 17.7055 16.8337 3.30774
298 1 13.1704 14.6146 7.25469
299 1 6.79813 16.1496 6.02021
300 1 1.60289 19.8553 8.41422
301 1 10.4789 19.4777 1.38497
302 1 4.82892 19.5946 7.01674
303 1 9.85289 17.5004 9.03844
304 1 9.10088 18.5214 8.51959
305 1 5.40945 16.6813 2.48356
306 1 1.71539 10.5493 2.01234
307 1 1.3298 10.0117 7.13286
308 1 15.3195 14.1468 4.60175
309 1 15.5086 13.8256 6.73938
310 1 4.89883 14.6035 0.224497
311 1 9.92166 13.3615 7.15524
312 1 1.7977 13.8765 2.296
313 1 18.0254 13.2792 3.07765
314 1 14.0214 17.5309 1.78991
315 1 3.73028 14.7753 8.01012
316 1 5.72476 16.0826 0.590185
317 1 19.237 15.869 9.51966
318 1 7.1208 19.3495 7.27497
319 1 14.1769 11.3811 1.75094
320 1 12.6775 10.615 5.80996
321 1 2.48918 15.669 9.61238
322 1 15.2658 12.5936 1.17305
323 1 10.8963 14.4753 7.09389
324 1 7.05127 10.6685 4.99968
325 1 16.8008 11.3779 8.95175
326 1 14.0294 11.6825 8.38572
327 1 18.76 18.8759 8.08581
328 1 14.4747 16.0199 6.34256
329 1 19.3618 13.409 5.30497
330 1 12.8383 13.4768 4.49688
331 1 3.99814 16.7661 8.68126
332 1 3.29736 18.7256 1.50105
333 1 14.9185 15.9343 7.47772
334 1 19.075 14.2041 8.66597
335 1 8.97454 15.0158 9.81456
336 1 8.93858 10.6507 6.09217
337 1 6.43377 12.3298 6.72499
338 1 11.4994 10.672 3.54139
339 1 0.182798 12.281 6.94756
340 1 7.7027 19.2292 5.50371
341 1 12.6228 11.3969 8.43964
342 1 5.04852 10.5587 0.808586
343 1 15.9241 15.9757 3.08996
344 1 0.161309 11.1138 9.49998
345 1 6.20881 11.4393 0.0705798
346 1 18.8488 11.23 1.83475
347 1 16.6878 12.6928 7.37968
348 1 2.23312 12.1133 7.46752
349 1 6.52675 15.0477 6.74278
350 1 0.02472 15.4689 6.08305
351 1 1.882 10.7325 0.987084
352 1 9.91681 11.8344 0.64691
353 1 8.3329 11.0503 2.11767
354 1 1.5977 12.5273 6.09732
355 1 7.3409 18.5892 9.124
356 1 7.0815 18.7487 9.2989
357 1 6.65891 16.222 3.38267
358 1 18.2338 14.837 5.59713
359 1 18.4823 12.7664 5.25881
360 1 13.9735 12.0134 9.6212
361 1 12.9299 12.9938 6.00322
362 1 4.55643 19.8967 3.43166
363 1 17.2663 14.761 7.53647
364 1 5.52 14.5873 9.04127
365 1 8.36621 10.9149 7.23819
366 1 12.2601 15.8606 8.29549
367 1 3.46256 15.2783 3.17055
368 1 7.42386 12.7437 4.04529
369 1 9.51743 19.4006 5.32022
370 1 16.8749 15.822 0.154405
371 1 1.58267 19.9124 8.29431
372 1 2.39751 14.9905 5.26752
373 1 4.86694 18.6761 8.69053
374 1 15.43 12.7417 9.11558
375 1 17.1304 11.3085 1.57818
376 1 4.43227 13.1911 3.29874
377 1 17.5484 15.6856 7.43393
378 1 2.08461 16.1057 7.76709
379 1 1.47741 10.7543 7.63902
380 1 7.41656 10.1592 5.03885
381 1 17.4388 13.5708 4.67136
382 1 15.8431 14.3873 7.42815
383 1 4.99522 14.5979 6.39103
384 1 18.5469 17.7225 2.58411
385 1 6.34837 16.9998 15.7158
386 1 14.6141 19.5382 18.5173
387 1 7.88908 11.7356 19.4078
388 1 7.5717 17.633 18.5331
389 1 14.3903 17.6032 16.3858
390 1 1.1347 10.9452 16.1006
391 1 0.938725 17.1579 13.0118
392 1 14.2937 14.3059 18.6419
393 1 14.0297 16.481 16.8344
394 1 15.8239 11.6343 16.9061
395 1 4.5562 16.1035 12.3273
396 1 5.39054 18.8266 18.8324
397 1 5.05209 10.4361 19.5951
398 1 9.38742 14.3066 11.0374
399 1 6.20928 19.3024 16.0863
400 1 13.8248 12.5895 11.0455
401 1 16.0764 16.3498 11.6522
402 1 9.80286 16.6497 11.1099
403 1 3.59804 12.2637 16.8237
404 1 6.9017 16.8211 12.8035
405 1 4.10502 13.0024 11.6682
406 1 13.1907 15.5905 10.3626
407 1 4.83805 13.0273 10.1074
408 1 18.9216 15.4633 12.4841
409 1 1.3846 10.8952 15.7445
410 1 9.51489 16.7127 10.8701
411 1 13.4297 12.8884 15.8454
412 1 0.158262 19.9019 11.9833
413 1 2.78302 14.301 17.6526
414 1 17.1283 15.0697 16.8962
415 1 17.8376 16.3547 13.9053
416 1 8.04899 19.3547 15.0986
417 1 1.95371 15.981 12.5314
418 1 12.3459 17.1674 12.0828
419 1 4.4835 14.2558 17.0265
420 1 11.3901 13.2165 10.4856
421 1 17.6437 17.9946 15.0298
422 1 5.48297 12.2258 19.4366
423 1 18.1494 17.5509 17.5892
424 1 17.9515 10.6906 16.8538
425 1 1.93251 19.696 10.9868
426 1 15.8966 14.8188 18.8611
427 1 2.92489 18.6112 17.9329
428 1 10.2216 14.5115 13.9438
429 1 3.12313 10.4916 12.2671
430 1 17.8301 10.8523 14.9807
431 1 16.9424 11.0439 14.7086
432 1 13.7752 19.5023 15.972
433 1 1.53337 11.3629 16.1996
434 1 7.11588 16.6642 15.8047
435 1 18.73 15.0138 17.3929
436 1 2.17756 18.305 12.091
437 1 19.5569 12.0698 17.4183
438 1 4.99293 16.094 12.0424
439 1 7.98778 10.6633 18.7168
440 1 8.95677 16.4024 14.4463
441 1 3.83248 12.5267 15.8578
442 1 3.77784 14.1201 16.3253
443 1 19.6949 12.8325 15.5818
444 1 9.63522 19.1347 16.4418
445 1 16.3872 18.9134 18.0624
446 1 19.475 16.2357 14.0438
447 1 0.644386 10.1916 10.381
448 1 14.1355 15.8917 11.9921
449 1 11.8184 11.5701 18.2336
450 1 19.057 10.5765 19.6676
451 1 12.9215 12.1687 19.7662
452 1 8.21037 11.6104 15.9618
453 1 10.7407 19.0428 12.8229
454 1 8.93381 10.4944 19.7428
455 1 17.3759 16.5573 19.3418
456 1 19.0951 11.6366 16.725
457 1 16.432 12.8966 13.3575
458 1 12.3253 11.9746 16.4146
459 1 19.8487 17.1411 10.3769
460 1 0.102162 17.0425 13.1548
461 1 6.23387 12.5958 17.295
462 1 10.2098 15.3804 19.0774
463 1 17.0916 18.3244 18.8083
464 1 10.9641 14.1199 13.6521
465 1 16.4166 14.159 10.912
466 1 18.7731 19.2455 19.6786
477 1 19.0075 19.8498 16.391
468 1 4.2196 18.8845 12.3156
469 1 7.95848 18.1704 10.3379
470 1 9.63476 11.3368 17.4512
471 1 4.56804 15.0361 11.3953
472 1 9.04814 12.0136 13.3348
473 1 11.1239 19.0418 16.1596
474 1 0.418515 13.9782 11.1527
475 1 3.95037 13.8987 15.2076
476 1 1.23508 18.0567 18.7692
477 1 3.99915 13.7879 12.8475
478 1 7.13848 16.3832 13.0561
479 1 19.5534 14.3355 16.309
480 1 4.9713 12.6647 14.9126
481 1 6.96705 15.1492 12.9628
482 1 18.7418 13.7225 14.4802
483 1 4.76192 13.5689 11.9944
484 1 9.64589 18.423 15.6616
485 1 1.68231 14.5672 10.1578
486 1 10.7264 18.0329 19.2521
487 1 10.0541 19.0645 16.8209
488 1 8.37451 10.3559 12.3327
489 1 18.6884 15.3698 19.4839
490 1 5.252 10.3606 10.6548
491 1 4.5193 15.8428 10.0956
492 1 16.0312 16.2264 17.07
493 1 2.56634 12.3992 13.2085
494 1 12.6709 19.2739 16.6207
495 1 4.43211 10.4265 18.8905
496 1 11.4805 11.9885 10.0384
497 1 14.6972 16.1133 15.4457
498 1 0.480741 19.8079 11.6138
499 1 10.386 18.1945 14.8745
500 1 0.823443 19.6021 13.2304

Hi,
      What does the error message say? if it says unknown identifier, then try this, it might work.

copy the header of atom file from any example files of LAMMPS directory.
use editor to edit the values
run
~Priyank

Hi,

this error is because you need to ident your atoms-lines with 3 blanks (at
least this works for me).

Hope this helps,

Manuel

P.S.: I desperately try to post smth to the lammps mailing list, but my
mails never show up there, although I signed up. Do you know what I could
do? Or how did you manage to get your questions posted? Thanks for your
help!

Dear lammps users,

I try to calculate the heat of formation for organic molecules using the
ReaxFF in LAMMPS at 298K and 1 atm. However, the numbers I obtain do not
match with literature data, and I am unsure whether my input script is
correct (since I am new to LAMMPS). Enclosed you find my current
input-script below ("in.CHO"). Running it with methane (as in the example
"ch4.CHO" below) results in an energy of -641 kJ/mol instead of -74 kJ/mol
as literature value.

So I have 2 questions:

1. Is my input script generally correct for determining heats of formation?
I am afraid that not.
2. What needs to be changed in order to obtain correct heats of formation at
300K and 0 bar?

I really appreciate your help and look forward to your response(s)!

Best regards,

Manuel

in.CHO:

units real

atom_style charge

read_data ch4.CHO

pair_style reax 10.0 0 1 1.0e-5
pair_coeff * * ffield.reax 1 2 3

neighbor 2.0 bin
neigh_modify every 1 delay 0 check yes

min_style hftn
min_modify line quadratic

thermo 1

fix 1 all box/relax iso 1.0 vmax 0.1

velocity all create 298.0 1 dist uniform

thermo_style custom etotal temp press

minimize 0.0 1.0e-12 1000 100000

data.CHO:

6 atoms

3 atom types

-35.0 35.000 xlo xhi
-35.0 35.000 ylo yhi
-35.0 35.000 zlo zhi

Masses

1 12.0107
2 1.00794
3 15.9994

Atoms

   1 1 0 -0.66680 -0.00245 0.01504
   2 1 0 0.66751 0.00246 -0.01507
   3 2 0 -1.24892 0.14516 -0.89008
   4 2 0 -1.20632 -0.15420 0.94555
   5 2 0 1.20590 0.15412 -0.94506
   6 2 0 1.24863 -0.14508 0.88963

Dear lammps users,

I try to calculate the heat of formation for organic molecules using the
ReaxFF in LAMMPS at 298K and 1 atm. However, the numbers I obtain do not
match with literature data, and I am unsure whether my input script is
correct (since I am new to LAMMPS). Enclosed you find my current
input-script below ("in.CHO"). Running it with methane (as in the example
"ch4.CHO" below) results in an energy of -641 kJ/mol instead of -74 kJ/mol
as literature value.

So I have 2 questions:

1. Is my input script generally correct for determining heats of formation?
I am afraid that not.
2. What needs to be changed in order to obtain correct heats of formation at
300K and 0 bar?

I really appreciate your help and look forward to your response(s)!

Best regards,

Manuel

P.S.: Sorry if you reveive this message more than once, but I had heavy
problems posting to this list.

in.CHO:

units real

atom_style charge

read_data ch4.CHO

pair_style reax 10.0 0 1 1.0e-5
pair_coeff * * ffield.reax 1 2 3

neighbor 2.0 bin
neigh_modify every 1 delay 0 check yes

min_style hftn
min_modify line quadratic

thermo 1

fix 1 all box/relax iso 1.0 vmax 0.1

velocity all create 298.0 1 dist uniform

thermo_style custom etotal temp press

minimize 0.0 1.0e-12 1000 100000

data.CHO:

6 atoms

3 atom types

-35.0 35.000 xlo xhi
-35.0 35.000 ylo yhi
-35.0 35.000 zlo zhi

Masses

1 12.0107
2 1.00794
3 15.9994

Atoms

   1 1 0 -0.66680 -0.00245 0.01504
   2 1 0 0.66751 0.00246 -0.01507
   3 2 0 -1.24892 0.14516 -0.89008
   4 2 0 -1.20632 -0.15420 0.94555
   5 2 0 1.20590 0.15412 -0.94506
   6 2 0 1.24863 -0.14508 0.88963

How does simply minimizing the energy of a configuration
give you a heat of formation?

Steve

I tried with H2O, CO2 and O3, where all resulting energies were close to the
literature data of Hform. So I supposed this would be the right strategy. In
case of methane, however, deviation was large. I agree that simply
minimizing the energy of the system does not necessarily give the heat of
formation, as it is defined to be the energy necessary to create one mol of
a substance from the elements in their most stable form. So I minimized
systems of hydrogen and carbon (where the latter didn't work), and tried to
subtract the values, but the numbers (even without carbon) indicate that
this is also not the right way. Therefore my question if somebody can give
me a hint, since I want to avoid working myself deep into the
forcefield-theory, since I don't really need it for anything else.

Thanks,

Manuel