Dear All,
First, I apologize if this post is a bit off-topic here, I was somewhat confused where to put it. I try to find a transition state for the reaction between gas-phase H2 and N2 adsorbed at Zr2Pd2 cluster which, in turn, is adsorbed at MgO surface. The whole system looks like this: H2 + N2Zr2Pd2/MgO. I use Turbomole 5.10, B3LYP-Gaussian/TZVP level of theory. MgO surface is represented using the embedded cluster approach: Mg13O13(Mg2+)16 cluster surrounded by 14x14x10 array of point charges. I used two different approaches according to 'Turbomole Tutorial', Chapter 7:
1. Running geometry optimizations using 'jobex -ri -c 500 -statpt' command;
2. Running usual geometry optimizations for different values of fixed internal (reaction) coordinate; in this case, I froze different values for the N-H distance.
Below is the beginning of my 'coord' file which I used in optimization with a frozen reaction coordinate, in this case R(N-H) = 1.40 A.
$coord
2.94269650799085 8.70517256995312 -6.12662777110223 h t
3.18795165995312 8.69023017323135 -4.16985475271014 h t
1.24346929104243 4.66952508859644 -6.81867974430503 n t
1.85514755869715 6.72906299183727 -7.51089310928279 n t
0.49315921621146 1.63177545661267 -3.47573169385390 zr t
-2.85469966556776 6.27129664797215 -2.07024114651313 pd t
2.26448474849826 6.72860502838286 -3.33985625474087 zr t
4.81146672690398 2.59188127870774 -1.95584133840447 pd t
-1.64765780569636 0.65589780882514 6.53548878831011 mg f
-1.03875796590770 3.41041959498460 3.72818956137744 o f
-3.94299388891248 -1.40196558549630 4.01842292360774 o f
-3.33410249629819 1.35254277554554 1.21117991834791 mg f
-6.23825076356201 -3.45985916469058 1.50136538497266 mg f
-5.62934072925756 -0.70531234597598 -1.30586730769249 o f
1.54604576628047 -1.34823406228030 5.26170980299269 o f
2.15498555885123 1.40625771444448 2.45442258078541 mg f
-0.74926538698186 -3.40611843293943 2.74471717940594 mg f
-0.14038863199110 -0.65177377696937 -0.06255879804864 o f
-3.04454077059504 -5.46401164965800 0.22762311320849 o f
-2.43562634099820 -2.70950812581347 -2.57964196704852 mg f
4.73973774420027 -3.35242818519170 3.98799096601442 mg f
5.34865687937156 -0.59795747135922 1.18073246081783 o f
2.44438751559923 -5.41031261914728 1.47096947823921 o f
3.05334040410747 -2.65580407722876 -1.33628490392127 mg f
0.14913623454979 -7.46815206343715 -1.04611251079960 mg f
0.75810060596027 -4.71364594153782 -3.85341083254211 o f
6.24705006254592 -4.65997339231836 -2.61006583912521 o f
5.63808738999613 -7.41451452578863 0.19720443848056 mg f
-6.52781052565389 3.35667156468916 2.48497024080376 o f
-7.13669874129849 0.60218933878025 5.29219982320310 mg f
-4.73092889673882 -4.76735305138602 -5.09671535499758 o f
4.45027941360410 3.46412001117776 4.97145718378342 o f
-5.33984762642259 -7.52187762848530 -2.28945459348295 mg f
3.84133699007477 0.70963530680147 7.77878599317138 mg f
9.44074474664376 -6.66419698257034 -3.88378453590872 mg f
3.95178093634575 -6.71784350909920 -5.12715179684097 mg f
-1.53721672926600 -6.77151509209041 -6.37046915690354 mg f
-7.02619340471186 -6.82521071830914 -7.61379224995092 mg f
-9.72151467196955 5.36080519717668 3.75873050915150 mg f
-8.82306207140230 1.29879103874416 -0.03211835900539 mg f
-7.92461235284285 -2.76320418409085 -3.82295975021676 mg f
-4.23249713250060 5.41458640182631 5.00200551620149 mg f
1.25652345365330 5.46828869116268 6.24524183595528 mg f
6.74554437497941 5.52201956845854 7.48849475486438 mg f
7.64397813705509 1.45993060886613 3.69777275890189 mg f
8.54234682915398 -2.60213163654589 -0.09299978879251 mg f
1.83546699765317 -8.16478517605102 4.27824742115336 mg f
-4.55185918267220 -4.15647967484167 6.82569557458534 mg f
-3.65349968604081 -8.21851041862997 3.03486530638247 mg f
0.93711555369754 -4.10271922471481 8.06903343472943 mg f
$intdef
# definitions of internal coordinates
1 f 1.0000000000000 stre 1 4 val= 2.64650
$redundant
number_of_atoms 50
degrees_of_freedom 144
internal_coordinates 323
frozen_coordinates 1
Values of frozen coordinates
2.64650000
# definitions of redundant internals
. . .
However, with both approaches my attempts to find the transition state fail: the geometry optimizations do not converge, energies acquire some wild values, and upon optimization Zr2Pd2 cluster actually starts to 'break apart'. Below, for illustration, I provide the 'energy' file from the calculation where the above coord file was used:
energy SCF SCFKIN SCFPOT
1 -7296.068737929 6975.991689638 -14272.06042757
2 -7296.778232386 6976.046454267 -14272.82468665
3 -7296.778237618 6976.045515165 -14272.82375278
4 -7304.626661321 6964.224106579 -14268.85076790
5 -7304.570183169 6964.280791980 -14268.85097515
6 -7304.110230526 6964.637134801 -14268.74736533
7 -7303.618275641 6965.088888878 -14268.70716452
8 -7302.817785988 6965.867585718 -14268.68537171
9 -7302.040314371 6966.785363475 -14268.82567785
10 -7301.317276263 6967.845136555 -14269.16241282
11 -7300.690202190 6968.975509339 -14269.66571153
12 -7300.152165210 6970.149115120 -14270.30128033
13 -7299.663959909 6971.401397695 -14271.06535760
14 -7299.274257447 6972.587350278 -14271.86160773
15 -7298.985198441 6973.633912647 -14272.61911109
16 -7298.771595323 6974.517172646 -14273.28876797
17 -7298.587633749 6975.323610256 -14273.91124401
18 -7298.420459703 6976.082314251 -14274.50277395
19 -7298.313181904 6976.656033577 -14274.96921548
20 -7298.196361295 6977.252256625 -14275.44861792
21 -7298.090702828 6977.797583921 -14275.88828675
22 -7297.987411844 6978.338275607 -14276.32568745
23 -7297.885879378 6978.873459102 -14276.75933848
24 -7297.777313753 6979.371389488 -14277.14870324
25 -7297.655418047 6979.902718588 -14277.55813664
26 -7297.512554292 6980.456938386 -14277.96949268
27 -7297.358989750 6981.027905511 -14278.38689526
28 -7297.200292473 6981.603972026 -14278.80426450
29 -7297.043155271 6982.131841291 -14279.17499656
30 -7296.868035994 6982.688447779 -14279.55648377
31 -7296.701331935 6983.194594431 -14279.89592637
32 -7296.524166590 6983.722744185 -14280.24691078
33 -7296.360705390 6984.210813430 -14280.57151882
$end
For reference: the total energy of the (H2 + N2Zr2Pd2/MgO) system is about -7300.963 A.U. at the level of theory used. With the "statpt" option I also obtained very strange energies which are even not close to this value.
I apologize for such a long post, I understand that finding a transition state for a on-surface reaction using the embedded cluster approach could be a relatively trivial/simple task, but I have been dealing with this issue for quite long time, and still without any success. Could anybody please help me here?
Thanks a lot in advance!
Sincerely,
Aleksey Kuznetsov.
