1. Is there a function you have written for spin-locking? I had an impression there is, but I cannot find it.

2. Is there a way now to conveniently extract the density matrix information from the tensor operator basis to the zeeman base matrix? I built each state like the singlet state before, but it is tedious for larger spin system.

3. I noticed in the JACS paper, you use M06/cc-pVTZ to simulate the system, have you compared the performace with b3lyp or other functional/basis set combination?

## Some practical questions

### Re: Some practical questions

1. Spin locking implementation depends on what you need to do – in many cases it simply amounts to putting all Zeeman interactions to zero for a period of time. Which experiment are you simulating?

2. Yes – the current development version of Spinach can run calculations in both Zeeman and spherical tensor basis sets, you just flick a switch. The operators in the Zeeman basis are built in the usual way with direct products of Pauli matrices followed by the transformation into Liouville space.

3. Accuracy of quantum chemical CSAs is a bit of a black art, unfortunately. See the last two lectures in the Quantum Chemistry course at http://spindynamics.org – the question of “what works” is basically empirical, and many methods produce right answers for wrong reasons due to error compensation.

2. Yes – the current development version of Spinach can run calculations in both Zeeman and spherical tensor basis sets, you just flick a switch. The operators in the Zeeman basis are built in the usual way with direct products of Pauli matrices followed by the transformation into Liouville space.

3. Accuracy of quantum chemical CSAs is a bit of a black art, unfortunately. See the last two lectures in the Quantum Chemistry course at http://spindynamics.org – the question of “what works” is basically empirical, and many methods produce right answers for wrong reasons due to error compensation.

### Re: Some practical questions

Thank you very much for your reply! Let me make sure I understand it right first.

1. I am trying to see spin locking effects on the singlet states. So for example after the M2S sequence I need to quench the chemical shift difference so that no leakage happens from the singlet to the triplet due to the coherent mixing. Please let me know how to implement that in spinach.

2. For the DFT, I guess I will run some training set to see if they make a systematic difference.

1. I am trying to see spin locking effects on the singlet states. So for example after the M2S sequence I need to quench the chemical shift difference so that no leakage happens from the singlet to the triplet due to the coherent mixing. Please let me know how to implement that in spinach.

2. For the DFT, I guess I will run some training set to see if they make a systematic difference.